Did you check the battery with a volt meter, it could have been drained down.
Interior lights are controlled by the etacs not the ecu, and if the etacs frys the interior lights are on constantly unless switched off.
I suspect the water got to the starter and since it has a straight power to the battery and the car itself is a ground drained the battery. Being that your jumping it that car does not have enough power to keep that car running and crank your car, especially if your using store bought jumper cables.
I would pull the battery have it reconditioned (a 24hr procedure) then charge it and put it back in.
what fox says is a last resort, not only can you get hurt but even if you do it right the current flowing through the temporary connection you make screws up the bolt threads on the starter. (because of the archs when applying the connection and removing the connection)