Do not try to power it on. That may further damage the circuits inside by sending electricity down routes it shouldn't take.
If you can, gently take it apart and let it dry for a long while, ideally near silica dessicant packets. You can later manually remove any debris/minerals left behind by the water with a swab and isopropanol.
If you cannot take it apart, then letting it dry as is will take a while and the chances of it working will be lower, but you can still try it.