2012 Yamaha 200 trim problems

Hi all

I have a 2012 Yamaha 200 where the trim is having problems.

I had the dreaded flat battery sound where the motor locked into the up position and then would no work at all.

we pulled the motor out, opened the electrical unit and cleaned the contacts. Trim Motor immediately worked. checked fluid levels, all good, no air.

put the motor back into the water, trim worked up and down. Docked the boat with motor down and trim stopped working. No electrics at all..

anyone experienced something similar?
electrical harness perhaps?

cheers
Brett