Nice that you could get it fixed.
The best thing a person can do when they move into a place is to make a Map of their Electrical wiring.
It is Great for safety and keeps you from working on the unknown.
Flipping breakers and checking outlets and lighting fixtures is easier when everything is working. It is best to have a drawing for next time something don't seem right.
It it harder to work on something that is broke, if you don't know how it should work in the first place.
Working on the wrong circuit would not give me a warm fuzzy feeling, Or could it ?
I would recommenced operating the heater on Low.
I use the ones with a 750 Watt setting, they seem to be safest. None of them should be left unattended.
Glad to hear you have it fixed and lived too tell about it.