Need a like button, couple of likes in this thread.
Our monaco has physical rotary battery switches in the battery compartment. Off cuts all power to/from that battery bank. Converter/inverter still works, still have full 12v power if plugged in.
First moho, a 99 pace arrow gasser, had switches in a cabinet above the door that controlled relays, possibly labelled use and store or something like that, it's been a while.
It sounds very much like your house batteries are completely dead, or switched off.
Start by finding the batteries, checking the voltage of each battery, charging them with an automotive battery charger if you have one, then move on to tracking the current path from the batteries to the coach distribution panel.