If your iPhone 6S keeps dropping dead on you, it may have a faulty battery. According to Apple, this problem affects "a very small number" of iPhone 6S handsets manufactured in September and October of 2015. Customers with an iPhone 6S from this period may be eligible for a free battery replacement from Apple.
Find your serial number
Apple has set up a support page for its iPhone 6s Program for Unexpected Shutdown Issues where you can enter the serial number of your iPhone 6S to see if it qualifies.
To find your iPhone 6S's serial number, go to Settings > General > About.
What to do if you need a new battery
If you qualify for a free battery replacement, you can take your iPhone 6S to an Apple retail store or an Apple authorized service provider, or contact Apple Support about sending in your phone for repair.
Apple suggests you do three things before taking your phone in for a battery replacement:
- Back up your data to iTunes or iCloud.
- Turn off Find my iPhone.
- Erase data and settings in Settings > General > Reset > Erase all Content and Settings.
If you are hoping to sneak in a fix for a cracked screen or other body damage to your iPhone 6S with the free battery replacement, I have bad news for you. Apple plainly states that it may charge your for such repairs before it swaps in a new battery.