Samsung charges back

The rhythmic thrum of the overhead propellers sends shock waves through my body, while a high-pitched whine hurts my ears.

Thwap-thwap-thwap-thwap. Wheeeeeeee! Thwap-thwap-thwap-thwap. Wheeeeeeee!

I jam bright orange earplugs in my ears, but that only muffles the painful ringing. Two minutes later, my stomach lurches as the 11-passenger AgustaWestland AW139 helicopter soars over Seoul's skyscrapers and heads south. Our destination is Gumi, South Korea, about 140 miles away.

I've traveled nearly 6,000 miles from San Francisco to get there, the site of one of Samsung's nine factories building phones and tablets. I'm among the first reporters to get an inside look at the company's flagship Galaxy S8 -- making its debut Wednesday in New York -- and to tour a facility that's testing the phone.

Samsung isn't throwing open its doors because it's feeling generous. It's trying to salvage both its reputation and consumer trust after dozens of videos, photographs and reports last year showed the Galaxy Note 7 bursting into flames. Samsung identified the battery as the culprit and -- less than a month after the Note 7's high-profile, mid-August release -- recalled the nearly 2.5 million units on the market.

And then it happened again. Some of the "safer" replacement phones went up in smoke, too.

Samsung knew it had messed up. Badly. So after two recalls, the company killed the Note 7 in October 2016. The debacle cost Samsung an estimated $17 billion in sales. It also cost it the lead in the global smartphone market, with Apple leapfrogging Samsung in the fourth quarter of 2016 to become the world's biggest smartphone vendor. (The last time Apple held the lead was in 2014 when it introduced its first big-screen phones, the iPhone 6 and 6 Plus.)

"It was an eye-opening experience," Koh Dong-jin (better known as D.J. Koh), head of Samsung's mobile business, tells me from Samsung's sprawling Digital City campus in Suwon, about 21 miles outside of Seoul.

"Afterward, I set up a principle: Meaningful innovation should keep going where we can make our customers happy continuously. But on top of it all, keep as a top priority customer safety," Koh says the day before my helicopter flight. "I strongly believe I can bring our customers' trust back."

Which is where my visit to South Korea comes in.

The Galaxy S8 could be Samsung's single most important product. Ever. The slab of metal and glass with a 5.8-inch display (6.2 inches for the S8 Plus) has to perform flawlessly with nary a whiff of smoke, while wowing consumers with its sleek new screen and advanced features, including a digital voice assistant named Bixby. If the S8 delivers, Samsung just might pull off one the biggest comebacks in corporate history, regain consumers' trust and vault past archrival Apple ahead of the 10th anniversary iPhone -- expected to be a doozy -- later this year.

"The Galaxy S8 was always [going to be] a big deal, but after the Note 7, it puts more pressure on Samsung," says Neil Mawston, an analyst with market research firm Strategy Analytics. "If they get it wrong, it would have catastrophic effects for their mobile business."

Safety first

A T-shaped bar inside a clear glass case slowly squeezes a battery against a big slab of metal that lines the floor. When the plates pull apart, the battery sticks to the bar instead of resting on the floor. After about two minutes, I see smoke. Suddenly, the battery turns red hot and bursts into flames.

I watch in awe -- and a bit of horror -- as the flame dies out, leaving behind a charred black husk of what used to be a Galaxy S8 battery.

I've never seen a battery explode before.

Fortunately, the explosion happened in the Gumi factory, where Samsung assembles 1 million phones a month. It's also where I see the company's extensive, new testing process. In this case, the battery caught fire because a factory worker applied 20 kilonewtons of pressure on it instead of the standard 13 kilonewtons. (A single kilonewton of force can knock down a 225-pound person.)

If the battery had been truly defective, Samsung would have sent the entire lot back to its supplier, potentially as many as 15,000 units. "It very seldom happens," a worker in Samsung's durability testing lab tells me.

In January, Samsung revealed the Note 7 battery fiasco stemmed from two separate issues. The external casing of the first battery was too small for the components inside, causing it to short-circuit and ignite. The supplier of the second battery had introduced a completely different manufacturing defect that led to the same result.

"That was a very painful experience, a painful accident," Koh says, echoing his comments from January.

Samsung realized none of its previous checks would have caught those problems. So it changed the process, instituting an eight-point inspection test that includes some steps that were new and others its suppliers had conducted.

During my three hours in Samsung's Smart City campus in Gumi, just five miles from South Korea's scenic Mount Geumosan provincial park, I see most of those tests in action. The battery compression test, for example, is part of Samsung's durability check. Samsung conducted those tests before the Note 7's problems, but now does them more regularly.

"The emphasis is to make sure the batteries don't have any problem," says Daniel Lee, director of global manufacturing and innovation.

Step it up

In the factory, Lee literally walks me through Samsung's assembly process and eight-point safety check. Durability tests examine batteries that have been overcharged, punctured or exposed to extreme temperatures. One machine is set to 130 degrees Celsius (266 degrees Fahrenheit) for 60 minutes. Another bakes a phone at 70 degrees Celsius (158 degrees Fahrenheit) for seven hours.

Workers visually inspect each battery and take X-rays to look for abnormalities. They also disassemble batteries to examine overall quality. I don't get to see any X-rays but I watch two workers peel apart a battery in a well-ventilated room, using images and a checklist of a functioning battery as their guide.

As Lee and I walk along the factory floor, I spot large rows of phones being charged and discharged while they rest on black foam-covered shelves. It's one of the three new tests Samsung has added to the safety check. Samsung can run as many as 60,000 phones at a time through its charge and discharge test. It's checking 6,000 the day I visit.

Other tests look for leakage or voltage changes.

I step into an area that's been walled off from the rest of the open factory floor. It's much cooler in here to compensate for the heat generated by dozens of phones. Samsung's electronic, poppy ringtone, called "Over the Horizon," echoes around the room as one Galaxy S8 after another cycles through an automated software test. After the ringtone, a video pops up, then Angry Birds and then YouTube. The phones' software is simulating daily usage at a much faster clip than normal.

Workers, wielding orange laser thermometers, check to see if the devices are running hot.

Within 30 seconds, I realize I'd go crazy from all the random dings, chimes and "Over the Horizons" echoing across the chamber. But for some employees, spending time in that room is now part of their daily routine.

The phones are going through Android Control Tests, part of Samsung's accelerated usage process. Overall, it takes five days to complete this test, in part because there's no way to speed up a battery's discharge. Samsung plans to check up to 100,000 units this way before releasing them to customers. By the time of my visit, two weeks before the Galaxy S8 launch, it's tested 50,000.

Samsung's "doing more than all the right things, but how many years can they keep this up?" says Gerbrand Ceder, a professor of materials science and engineering at the University of California at Berkeley. He's also a member of Samsung's new battery advisory board.

Ceder visited the Gumi facility the day before I did. "At some point someone will say this costs a lot of money. But they cannot afford any problems with the Galaxy S8."

Bad news

Samsung has an interesting history with fires.

In 1995, Chairman Lee Kun-hee (who still holds that title despite being in a coma since his 2014 heart attack) discovered the Samsung phones he'd handed out as New Year's gifts didn't work. He was outraged.

So Lee traveled to Gumi, where he had 150,000 phones dumped onto a field as 2,000 workers watched. Then according to legend, he ordered some employees to set the pile on fire and others to plow over the charred remains with a bulldozer.

"If you continue to make poor-quality products like these, I'll come back and do the same thing," he reportedly said.

Since that moment, Samsung has stressed quality in its devices, helping it to earn the title of world's biggest phone maker in 2012. Lee never ordered another bonfire.

Last year's Galaxy Note 7 seemed like the ultimate manifestation of those ambitions. The phablet featured a curved 5.7-inch AMOLED screen and an iris scanner that let you unlock the phone with your eyes. It also boasted water resistance and a zippy stylus. Reviewers, including CNET's Jessica Dolcourt, called it one of the best phones ever made. You know what happened next.

But the Galaxy Note 7 isn't Samsung's only recent crisis.

Lee Jae-yong (also known as Jay Y. Lee), Samsung Electronics' vice chairman and heir apparent to Lee Kun-hee, has been linked to a corruption scandal that forced South Korean President Park Geun-hye out of office earlier this month. Samsung's de facto leader was arrested and formally charged in February with embezzlement and bribing Park to gain support for a 2015 merger that cemented his control of the company.

The day after I arrive in Seoul, I stumble upon thousands of people celebrating Park's impeachment in Gwanghwamun Square outside the historic Gyeongbokgung Palace. Bands entertain the crowd from a stage, as vendors sell snacks and cushions to make the day more pleasant.

Organizers pass out bright red signs that, translated from Korean, say, "This is how a country should be. This is justice." Later that week, I ask a woman teaching me Korean cooking what she thinks of Lee's part of the scandal. "We're used to it," she says. The elder Lee had been convicted of tax evasion in 2008, but pardoned the following year.

Samsung continues to maintain the younger Lee's innocence.

Beyond infinity

It's against that backdrop that I lay my eyes -- and my hands -- on the reason I'm here.

The Galaxy S8 feels different from any other phone I've held. It's much taller and narrower. What really catches my attention, though, is just how big that black screen is. It stretches nearly across the entire front of the phone, curving slightly around the long sides to give the effect it goes on forever. This is Samsung's new "Infinity Display," which builds on its earlier Edge curved screen technology. The Galaxy S8 and its larger sibling, the S8 Plus, ditch the physical home button so Samsung can cram the bigger screen into the device.

The frame around the display is almost nonexistent. In fact, 83 percent of the phone's front is screen. The Galaxy S8 is also 9.8mm (about 0.4 inch) narrower and 9.3mm (0.12 inch) shorter than Apple's iPhone 7 Plus, yet its display is larger -- 5.8 inches versus 5.5 inches.

The "contradiction" for consumers "is they want to have a bigger screen size but a small form factor," says Kim Gae-youn, vice president of Samsung's smartphone product planning and product manager for the Galaxy S8. "To solve that issue, we have to use the Edge technology."

And yes, of course, they addressed the battery.

Samsung says it's altered the battery so it starts with a lower capacity than the one in the Galaxy S7 Edge but should last longer because of energy management software and other tweaks.

After about six months of use, it will have better battery life than batteries in its previous devices, Samsung claims. That's because the company focused on making the battery more durable and able to withstand hundreds of charging cycles.

"Where most batteries hold about 80 percent of their charge after two years, this battery should be capable of 95 percent of its original capacity," says Oh Boo-keun, vice president of Samsung's mobile R&D team. He oversees the division's battery technology development.

While Samsung isn't giving up on the Note line (Koh says Samsung will create a Note 8), today is all about the Galaxy S8, its new mainstream phone.

It doesn't replace the Note 7, and it isn't that device's successor. The S and Note lines have coexisted since the first Note phablet went on sale in late 2011. But the truth is the S line has always been more important. The Note represents about 12 percent of Samsung phones in use globally, while the Samsung S models make up 60 percent, according to Creative Strategies.

The Galaxy S "is the big deal," says Creative Strategies analyst Carolina Milanesi.

I practice unlocking the phone using its facial recognition feature and examine what videos look like with its strange new screen ratio (18.5:9). The iPhone, in comparison, features a screen ratio of 16:9.

Samsung says its new size gives the "best experience" when watching TV shows and movies. You'll get black bars around videos you watch on the Galaxy S8, unless you're willing to zoom in and lose part of the picture around the edges.

Samsung has also changed the phone's software. A new Samsung Connect app lets you control internet-connected appliances and TVs from one place.

The Galaxy S8 also marks the debut of Bixby, a digital voice assistant. Like Apple's Siri, Amazon's Alexa and Google's Assistant, Bixby responds to spoken commands. Unlike those other smart assistants, though, Bixby focuses on controlling the phone, not answering questions like, "Who was the 30th president of the United States?" Bixby can do things like find and edit photos in your image gallery, as well as identify landmarks, types of wine and text for translation. It can also recognize photos of products and, in the US, send you to Amazon to buy them.

"A lot of [our competitors' AI assistants] are more glorified extensions of search," says Injong Rhee, head of R&D for Samsung's mobile software and services operations. "We're looking at revolutionizing the phone interface."

People looking for those handy search options on the Galaxy S8 can ask Google Assistant for help by pressing the phone's digital home button.

Rebuilding trust

Even with the flashy new features on the Galaxy S8, Samsung knows it has to work to win back customers.

"I won't ever use a Samsung phone again," says Ty Gates. The 26-year-old from Los Angeles says he can't shake off his battery concerns after his Note 7 overheated in his pants pocket one night while he and his girlfriend were out having dinner. The phone didn't catch fire, but it stopped working. "If that happened before, who's to say it won't happen again?"

Samsung is counting on its new safety check to "gain a little bit of trust," says Lee Young-hee, head of marketing for Samsung's mobile business. "Fortunately, we are seeing our customers generous enough [to say], 'I believe in Samsung. [It was a] one-time mistake.' That's what we are hoping for."

Mikey Martin, 21, is one of those customers. He held onto his Note 7 despite the two recalls and multiple incentives by Samsung to switch to another Galaxy device. Martin eventually gave the Note 7 up after Verizon disabled his wireless service. He's now using an iPhone 5C with a broken microphone as a holdover until the Galaxy S8 arrives.

"I bought the Note 7 because it was, in my opinion, the best hardware available at the time," Martin says. "I plan to buy the S8 at launch for the same reason."

Samsung hasn't yet said if it will offer special Galaxy S8 promotions for the millions of people forced to hand in their Note 7s. Preorders start Thursday, and the phones will hit stores on April 21.

CNET's Dolcourt calls the Samsung Galaxy S8's tall, curve-screen design a stunner, but worries that Bixby could stumble if Samsung doesn't address some weak spots in time.

A new "Dream"

Three hours after we touched down in Gumi, I rush back to the helicopter. The pilots are on a strict schedule, and we've got to get back to Seoul.

As the ground falls away, I'm reminded of something Koh told me the day before.

For him, the Galaxy S8 is more than just Samsung's newest flagship phone. It's the culmination of five years' work creating new hardware, software and services. The Galaxy S8 is THE device Samsung has been working toward for years, he said. It's only fitting the codename for the Galaxy S8 was "Dream."

"I do not want to boast, but I would say this is a starting point," Koh says. "We are on the [starting] line of the marathon."

But as anyone who's run a race knows, it's not how you start but how you finish that matters.

CNET News' Alfred Ng contributed to this report.