I would suggest reetting the circuit breakers. Turn all breakers off applying light pressure toward off. Turn on main breaker if equipped, then branch breakers one at a time.
Next would be to remove the cover over the 120 volt circuit breakers, With shore power disconnected, check for loose connections.
If you or son is comfortable while connected to shore power, check for shore power to the panel.
Is shore power hardwireed to the rig or does it have cord body connection on the side of the rig. Common for connections pull loose in connector.