[Scallywag2]

Start simple..Disconnect batteries. With a volt meter the voltage should be close to what you measured before you installed the batteries. Connect one battery. Use the black ground and 1 red wire. Turn the battery selector switch to both. Does anything work? If nothing works maybe the selector switch is bad. Disconnect everything and remove the selector switch. Use a continuity tester to see if the switch is good. I had mine fail. If it is good you need to trace the wiring. Is something disconnected?

Dot and John