I wonder if he tried to fix it. I believe the best method is to, first, take the battery out. Then remove excess water. If you can open it up, that should help. Let it air-dry. Mild warmth would be good, eg as from a 60 watt bulb, but he wouldn't have had that available (and a fire might do more harm than good). Wait until it is completely dry, put the battery back in and try it.

The water is unlikely to dissolve anything; the damage is usually caused by water being a good conductor and taking power to places it shouldn't go. That might blow an IC or something, destroying it permanently, but it might not, especially if it was switched off at the time. (But it's good to remove the battery quickly anyway.) ICs often have internal protection against static etc. Dirty water is worse because it is a better conductor. Also because it might leave deposits as it dries, so it can be worth rinsing the device in clean water (if you have it to spare) if you dropped it in the sea.

The upshot is that even if it doesn't work when wet it may work when dried again. If you have 6 days to kill it's worth a try.