Wait. Isn’t This Deeper Than A Simple Software Problem?
Yes. This isn’t your simple run-of-the-mill software problem where your battery is draining too fast because your apps are crashing. But it’s not necessarily a hardware problem either – so we need to address your iPhone’s firmware. So what is it? If it’s not “soft”-ware, and it’s not “hard”-ware, then its “Firm”-ware.
The Fix For iPhones That Turn Off With Battery Life Remaining
To fix the issue with your iPhone shutting off even though it says there is still battery life remaining, we’re going to do a “DFU Restore”. DFU stands for Device Firmware Update. A DFU restore reloads your iPhone’s software and firmware, so it’s an even deeper type of restore than the recovery mode Apple describes on their website. To learn how to DFU restore your iPhone, check out my article called How To Put An iPhone In DFU Mode, The Apple Way, and then come back here to finish up.