It's not always behind the hole to. Like when you say it can be hard to find he might need to use paper clip and go in a circle within hole trying to find it. Once he does find it though I would also ask him to make sure he's holding long enough. Some just press it and think it resets you have to hold longer then a instant push to do the reset I think hes going for.
Also don't know his firmware but one had a issue where you could not reset... so hope hes not on that firmware.
yeah yeah don't worry done it plenty of time.... I think the board is corrupted...
The board could have a problem, I once had one that messed up during a update and electricity was lossed. I bought a new S3+ IO board programed with firmware since mine was bad flash. If you have a bad flash or something it can be done with serial to usb cable I believe.
And there really was one firmware I believe reset button did not work so if you had that firmware it could be a issue there. Been a while since I messed with S3's.