By now everyone is pretty much aware that the Samsung Galaxy Note 7 has a tendency to spontaneously catch fire. But it's only after months of investigating that Samsung is opening up about why the recalled phone is overheating. And it turns out that it all comes down to poorly made batteries. Specifically there were two separated battery defects. One in the original batch of Note 7s and another in the replacement units. To understand what exactly went wrong, you have to understand what's inside a lithium ion battery. It may look like just a thin square, but inside it resembles something like this snack cake. Thin layers of positive and negative electrodes are folded up like a jelly roll with a super thin separator keeping the positive and negative layers from touching. If for any reason the folds aren't just right, and the layers get squished or if they touch, boom. You got a short circuit and a phone on fire. According to Samsung, the original batteries were a bit squished in the upper The right corner. And the tip of the negative layer curved over. Additionally one of the ends was sitting in the wrong spot of the fold. The second set of replacement batteries suffered a different problem. These came from another supplier and in the rush to pump out replacement batteries quickly, the manufacturer was sloppy, and the separator was punctured, leaving the layers touching. In some cases, there was even some insulation missing inside. To solve the mystery of the exploding phones, Samsung created a special facility to test more than 200,000 phones, and more than 30,000 batteries. Samsung also worked with three independent testing agencies. But, now, Samsung faces a bigger mystery. Will customers trust the brand again Here's the take from CNET Executive Editor Roger Cheng, who spoke with Samsung executives. So, I think, they're taking the right first step in being as transparent as possible. They're really going into detail, over sharing On exactly what happened to both the first and second batch of Note 7s. I think there's still a long road ahead of them when it comes to building back that credibility with consumers. To catch future mistakes, Samsung said it is implementing additional safety checks for batteries, such as beefing up the stress tests and x-ray exams, and charging and discharging the batteries on a large The upcoming Galaxy s8 and on8 will also go through this test. That's right, Samsung continuing the known brand with a new one. Believing that there are enough world fans who would give the phone another chance. From CNET, I'm Bridget Carey.