Don't try turning the phone on. If the battery can be removed, remove it and place it and the phone in a sealed bag or container of uncooked rice for 24 - 48 hours to try and dry them out.
Hobby Stores have a product called silica something used to dry flowers. It looks like salt but is not! What I bought came in a carton looking like a 1qt milk carton. First: with battery out and the phone open, wrap it in a paper towel and tape just to hold it in place. The tiny beads will get into buttons, etc if you don't cover it. Then put the still open but wrapped phone in a small mixing type bowl large enough to cover the phone with an inch or two of the beads. Then pour the beads in along the side of the phone trying not to hit it and fill it at least 1" (more is better) over the phone. Set it on a shelf somewhere and let it sit for 3 days. When you take it out be careful not to tear the paper towel. You do not want to get beads inside your phone.
Hope this works for you.