When an electronic device like a phone gets wet and shuts off, the common reaction is to immediately try and turn it back on, and then charge it to try and get it to turn on. Those are actually the worst possible things to do. It's best to have a spare backup phone around, dry the wet phone off thoroughly, pull the SIM card out and dry it off for the spare phone, leave the SIM tray out of the wet phone, get a blow dryer on low heat, and take as long as you're willing to, to warm up and dry out the phone.. being sure to direct plenty of air into the SIM card slot.
Then put it in rice for a few days, then another round with the blow dryer. That's not guaranteed to fix it, but it's worked for me. Trying to turn on and charge a wet phone causes short circuits everywhere, and can short out and destroy the battery instantly.