First things first: '''do not try to turn it on anymore until you're sure it's completely dry. Water isn't damaging to a device, electricity is, and water reroutes electricity where it's not supposed to go'''.
Until you can't get it open, put it somewhere dry, possibly surrounded by silica packs or (lacking them) rice.
As soon as you can, open it carefully, '''remove the battery''', and clean with isopropylic alchol and a microfiber cloth every trace of water. Don't use an hairdryer, at least, if you're truly in a hurry, blow only ''cold air, never hot air'', that could be as damaging as the water.
Make sure it's clean and dry, put it back, turn it on and reassess the damage.
You may end with a damaged battery, since it got shorted out. Maybe some other sympthoms... if you want to check them by yourself, return here and describe them.