Hi! The first thing to try is to test the memory. Often the edge of the memory modules becomes corroded when liquid enters the machine, and replacing the RAM, or even just cleaning it with rubbing alcohol and then powering it on trying one module at a time and one slot at a time (to test if a slot has been fried) can revive a water-damaged machine.

Also, I assume the computer has dried completely, but if not, definitely let it try before plugging it into the wall, or even connecting the battery. Connecting a wet or damp computer to power will fry the machine.