[stomachmonkey]

He should do nothing until he can get a backup.

Start with the force resets.

If the phone boots normally obviously do a back up immediately.

If the phone boots but you get no display try plugging into laptop and see if iTunes sees it. If yes try a backup.

His stuff may be backed up to the iCloud if he enabled it on set up, he should check that.

Good luck, hopefully the lesson is not too painful.