Logic board starts immediately when connecting magsafe

I'm replacing (what I think) a faulty keyboard. When I disconnect the keyboard from the logic board and put in the magsafe, the logic boards starts up immediately, so I don't need to jump start it on the logic board. If the keyboard is connected the logic board stays dead. The macbook pro had some water on the keyboard.

There is nothing else connected to the logic board, only the magsafe and the fans.

If I connect the magsafe, the fans starts spinning immediately.

Somebody know this is normal behavior?

Thanks, Geoffrey