Electrical short during hot weather, intermittently loses power while parked

Once I get it started it runs fine, and the problem always manifests itself while parked. Sometimes I have to use the key to open the door because the keyless entry has no power. Then I try to start the car and sometimes it starts right up. But it's inconsistent because sometimes everything is fine. Twice the power was fully not working, and then I'd lightly bump the steering wheel and the power came on immediately and started right up. This all occurs when the temperature outside is hot, like in the high 90's and 100's. But today, the temperature was 80 - 85 degrees, and no problems i.e. no power loss.

I've been tightening wire connections and checking relays. Haven't found the issue yet. Any thoughts would be appreciated. Thank you.