Unit does not respond to a/c input via shore power or generator. Switches from inverter mode to charge mode but The Mains light does not come on and then begin to charge. A/c circuits have no current. A/c loads not connected to the Multiplus work fine. Happened right after I may have overload the a/c draw - temp and low battery lights were flashing. Now the absorption and float lights just blink, now mains light. What could be the problem?