Restarting issue with HTC One M8 on Verizon

[StygianSentinel]

Hey all, I'm asking for some help on behalf of my boyfriend. His Verizon HTC One keeps restarting randomly. At first I thought it was just that restart bug that the Stop Restart app is supposed to fix, but apparently it already has that update from what he says. Soft resets don't seem to do anything, and he doesn't want to have to deal with the hassle of a hard reset, and the prospect is only made more painful by the fact that he is one of those types who doesn't trust backups/cloud storage. Any suggestions, or is a hard reset the best option here?