1986 ProV150 Tilting On Its Own

I have a 1986 ProV150 with a fairly new fully charged battery installed. The power trim/tilt operates all by itself. The boat was parked beside the house, (used about 3 weeks before it was parked). I heard an alarm and thought it was coming from the neighbor's but it was coming from the boat. Somehow the trim and tilt ran to the full up position. The battery was completely dead and would not hold a charge. I installed a new battery, cleaned the connections, put everything back together and everything seemed to work fine. About 20 minutes later I was in the house and heard the tilt mechanism running. Anyone have any ideas why this thing would tilt on its own?

Thanks

[boats.net]

Probably one of the trim switches are bad, possible water inside switch shorting it out.