When I turn on the IBBS it shows 12+ volts and 0 on the battery bus. Then when I turn on the master switch, nothing happens. Battery bus still shows 0, lights, fuel pump, etc. are not powered. Main 40 amp fuse is good, master switch in the panel tests good, main battery is good. I assumed the problem was the master relay so I replaced that but I still have the same problem. Suggestions??