Thanks for the attempted answer, Sterling. However, that troubleshooting checklist is irrelevant to the issue some of us are having.
I am experiencing experiencing a similar phenomenon with my iPhone 5. It will simply crash, hard and randomly. At first, it was very random; occurring maybe once per week or every few days. However, it has gotten to the point where it does so almost daily.
The crash is manifest as an unresponsive phone. If I press and hold the 'Home' button, the device suggests that it has reached a critically low power level presenting the 'Low Battery Indicator') and entered hybernation. Colet's suggestion that "[p]owering off the unit and turning back on used to fix the problem" has never been an option for me. The only solution has been to attach a Lightening cable to a power source. The phone then awakes from hybernation and resumes 'normal' operation.
Very rarley has this occurred as a result of the phone depleating its internal battery. In fact, it has occurred with power levels ranging from 13% to 93%. It seems to be an issue with the iPhone PMU (or its analog).
I have tried various methods to determine the cause of the anomaly. One predominant factor is the use of a GPS tracking app (e.g., Endomondo), but not always. This morning, I was simply walking up an internal staircase listening to a podcast. When it stopped, I first assumed that it simply lost the streaming source. However, when i arrived at my desk and attempted to restart the podcast stream, I discoverd that the device had crashed. Attaching it to power immediately revived the phone, which indicated an 88% charge state.
