When you loose power you start at the source and work your way to the item in question. Take a voltmeter or some other 110 item and check for power at the city connection. If you have power there plug the trailer in and go to the beaker panel and test for power on the input side of the breakers. If there is power there test the output side of each breaker. You do this until you find a spot without power. If you find the spot without power you repair from that point back to the last point you had power. It may be as simple as a popped breaker or a hard as a broken wire in the wall. But there is no simple way to bypass this procedure.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles