Water damaged MacBook, how to proceed?

I came into posession of a white macbook 2010 unibody with water damage (according to the owner).

I haven't opened it completely yet (only the backcover) and was wondering what the right way to move forward is?

The power connector's light does turn green when connected, but the macbook won't respond to power-on button, nothing happends.

The keyboard has some issues with keys, so I assume the liquid fell over the keyboard. Is it possible to power on a macbook without the keyboard? (Bypassing it?) Or would that not be of any influence/would the powerbutton not be damaged by a liquid spill?

I do have another logicboard laying here, but I would like to explore other options first.