[DVPete]

You need a voltage meter. It makes finding these electrical problems so much easier. They are relatively cheap and easy to find. I was surprised at how much I used one when I finally broke down and bought one.

Check the ressetable circuit breaker as flybouy stated above. It is the first component off the battery on the "+" cable. It doesn't even look like a breaker but it is and they are frequent failure items.

Not all RVs are wired the same but frequently not all items are disconnected by opening the battery disconnect. Since you stated that everything worked while plugged in I tend to think the disconnect is fine assuming it's on the positive side and doesn't isolate all loads when open (or broke).

A voltage meter will quickly prove or disprove the switch and the circuit breaker. Do these checks with the camper unplugged from shore power. Shore power would mask your indications.