My bets are on the capacitors being rated for 85CThe pushbutton isn't waterproof but it can be dried out. If you are worried, you can unsolder it while washing
I used to work in the Marine Electronics industry and was told that PCBs (and some components) will soak up water. I observed this during many years of humidity testing.Is cleaning a PCB with water a good idea then ? and surely not boiling
In one of those "how to build and update and repair a pc" books that were in vogue a while back (probably one of Mark Minasi's) the author advocated chucking boards in the home dishwasher.His boards were totally stuffed from being in a marine environment, and he was going to chuck them away as scrap. So as a last resort, nothing to lose, he stuck them in the dishwasher and after that they worked.YMMV, E&OE, Ts and Cs apply.