Some of these circa '70's trailers had a 12V system that was switched on the distribution panel faceplate to run either the 12V system or charge the battery. You could not do both at once. That might be part of the 12 V side not charging the batteries.
The 120V problem is probably due to overloading a branch circuit. Turn "off-on" all circuit breakers to reset them. There may also be a loose connection in the load center. The large draw of multiple appliances may have caused the last bit of connecting wire to disappear. I would check the load center wiring, anyway, as trailer wiring can vibrate loose. Tighten all connections in the load center (we don't need to tell you to disconnect the shore power when doing this?).