Ok, some logic
I do not know why the control panel went dark.. The lights there should be 12 volt
You had 12 volt power independent of the 120 volt (When unplugged) this eliminates the main battery fuse or breaker, Disconnect switch and in fact most of the 12 volt system.. IT DOES NOT eliminate the fuse for the thermostat or the fuse for the display panel/control panel
The converter may or may not be good.. Only way to test it is with a volt-meter which you did not have
Sounds like a 120 volt side issue.. Possible issues include
Tripped or failed circuit breaker All breakers are suspect
Screw loose.. Many Rvers have a few screws loose.. Story explains below
Bad wire (have seen that once) or broken wire (have read and seen both)
The story
When my RV was new sometimes the A/C's would work, sometimes one, or the other would not.. Was saving money on hair cuts trying to figure it out (Pulling hair out) when I thought to check the main power distribution panel.....
Well I notice a wire MOVE in the clamp.. That's strange I thouht. So I got out the old #2 Square bit screwdriver and (First unplugging from shore) Tightened everything in sight... One screw took over 2.5 turns before I even felt resistance and another full turn or so to tight.
Yup, that was it.