On the panel where you check the holding tank levels, one of the buttons will light up the battery level lights. When on shore power, this should display 4 lights, reflecting the output of the Power Converter and battery, not just the battery.
If you have 4 lights but the batteries are not charging, your Power Converter is working, but the power is not getting all the way to the battery. There is a row of 12V mini-circuit breakers (covered by a red rubber boot) near the battery. One of them has thick wires attached. That breaker will have a teeeeeeeeny tiny reset button. When that breaker trips, the path between Power Converter and battery opens up.
Another possibility is that your battery cutoff switch is OFF. If you have a residential refrigerator, you probably have 2 cutoff switches. One is dedicated to the refrigerator circuit and the other is for everything else.
If you don't have 4 lights, the Power Converter is not working. First thing to check is to see if all of your 120V AC devices have power. Check outlets in the bedroom, kitchen, and living room. Check the microwave. Check the TV. Check the air conditioner(s). If you find that some have power and some don't, one of the 2 legs of 120V AC power may be missing. When that happens, the Power Converter may not be getting 120V AC power.
If you have some 120V AC devices/outlets not working, first check that the power cord is fully twist-locked into the receptacle in the side of the trailer.
Sometimes when you use a stack of power adapters to go from a 50 amp plug to 15 amp receptacles, you can also have a problem where only 1 leg of the RV 120V AC system is getting power. The problem is typically in the 50-->30 adapter where the 1 hot wire from the 30 amp adapter gets shared with the 2 hot wires in the 50 amp plug. Only thing you can do to fix it is get another adapter. If you have a volt meter, you can check the power on the receptacle side of the adapter.
There's more information, including pictures and drawings, in our owner-written
Electrical User Guide.