How do you fix a key fob that has been dropped in water?

It might never work again, but the worst thing to do is to try and use it because if any charge goes through then it will fry it. If possible remove the battery, either way put the fob in a baggy or bowl that's filled with rice, this will remove all the moisture. Leave it in there for at least 24 hours.

You can also remove the battery and spray inside with an electronic cleaner which will remove the moisture.