Ok we bought a really nice boat that fired right up the day we bought it. Took it home put it in the water and ran great and then just died in the water. Kept trying to start it until the battery's died. Got it home, charged the batteries and then all we got was a click. Replaced starter, solenoid and still just clicks. Tried to turn fly wheel by the nut and won't move. Took out spark plugs put some mystery oil in and it turns very slow and takes a lot of strength to do it...any ideas??