[particlewave]

Water generally will not harm low voltage electronics, its the minerals and corrosion left behind. Remove the circuit board and soak in rubbing alcohol(no battery, of course) for a few minutes and then clean and scrub the board with a toothbrush and alcohol. Let dry for an hour and try again.

Most likely, though, the corrosion or short is in one or both buttons where water was trapped for a while. I would replace them. Only takes a few minutes and about $1 if you're handy with a soldering iron.