I wonder if you just have some oxidation going on in some of the electrical connectors and contacts causing bad contact. If you could get to the wiring pull the connectors apart and try a good electrical contact cleaner on all of them. I’ve seen it where something with low current draw (such as the display) will work fine through a bad connector but as soon as you have high current draw (motor on) the circuit breaks down and it all stops working.my bike is in a warm and dry office daily! the condensation on the screen so gone many months ago. but the power turn off. i guess i will really need to find a dealer.
Something like “Servisol Super 10” works very well on connectors because it cleans and provides a protective film. I don’t think it’s available in Canada though and I don’t know of an equivalent right now.