I was also getting a loud click through the radio whenever anything electronic turned on. So if I tapped the brake the radio would click. Move the power windows the radio would click ... indicators, headlights, etc etc etc

Not getting any radio noise at all since the new battery went in.

heres a good video I used a while back to look for parasitic draws. I dont know if thats your problem, but It sure sounds like something you should do either way with your 'wonky electronics'

How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

Is this with key on or key off? Key on it's normal...key off it's a clue something is not right. I had a drain for two years because Hella made a fog light relay harness with the wires in the wrong holes on the relay plug. This sent the entire current for the lights through the switch and left the relay coil energized 24/7. The lights worked and it was a daily driver so the battery never went dead until I went away for a week by plane. The foglight relay click on connecting the battery led me to the foglight circuit.

No relays should energize (click) when you connect the battery with the key off. If they do, the coil is draining the battery 24/7. Not good. Aux plugs and a few other will energize with key on.

Key off. I have Hellas that do not work. I'll try to see if I can undo that relay. That may be the source as the relay is right next to the battery.

Edit: that may be the relay I am hearing. Still is strange that it will have power and not start huh?