Since you can't trim (now) and can't get the motor to turn over, plus the electronics work and you've tried several batteries, I would start with wiring. Maybe corrosion in a wire or at a connector. Electronics probably runs off a different wire run than the motor. Take the cables off the battery and bend them back and forth as far back as you can reach. If you have an Ohm meter and know how to use it, Ohm the cable run for the motor.

If you can't find an issue with the wires, check out your control box. It's possible you have a wiring\corrosion issue in there. It would probably be a supply issue as you are having both trim and starting issues.