Everything was working fine, then I tried to install the Mysa baseboard heater v2 thermostats. When I realized that my wiring doesn't seem to support them, I put everything back together, and now of course nothing works at all (even the room/thermostat I didn't touch).
The wiring is from the '80s and I'm not entirely sure what's happening between the boxes. I've drawn up what I think is happening, but 1) I'm guessing, and 2) I don't know/understand which wires are going to the breaker (if it matters, basically I can't get my head fully around the whole circuit, which is making it hard to test).
I have a volt meter, but I'm not sure what's useful to test. I'm getting 120v on both legs at one of the heaters and it still isn't on. These are cadet fan units, I'm not sure which model(s). If the Mysa units will work that'd be great to know, but otherwise I'd like to get the old thermostats working again. Help? Thank you.
Living room, closest to breakers
Best effort at a wiring diagram. (Skipped extra lengths/wire nuts for 1:1 connections)