[Intar]

That is likely do to an buggy app causing a system crash or a jailbroken phone. Very unlikely due to a bad battery, but anything is possible.

[Pox]

Highly unlikely it's an app. It's certainly not jailbroken.

I'm not convinced it's the battery either.

I got my phone at the same time he did (they're both company phones) and he doesn't really do much with it outside of taking pictures and using it for its primary purpose.