Sorry for the delay, been trying to get this sorted out.
I did call BCS and talked through the problem with Ken, although we are stumped at this point. Situation is:
1. Total loss of power except the radio which is hot wired to the starter batteries.
2. The 20 amp breaker on the outside bay panel won't stay on most of the time, it will reset and then flip off within a few seconds.
3. The inverter isn't dead. As a workaround Ken suggested looking at the BD Relay and finding voltage on the input side. He also suggested jumping the relay using battery cables from the main coach positive terminal to the output side of the BD relay, apparently bypassing the relay. This brought up the inverter and we had 12 V power and 120V power to all but the fridge circuit.
This might indicate a dead BD relay. He also suggested jumping to the input side which had no effect, no power. He then suggested starting the generator. The jumpers were still attached to the input side of the relay. Lots of smoke and it burned the paint off the battery cable clamp. Too much power. We blew the 250 amp fuse at the coach side. Ken seemed to think there was a power short somewhere in the power lead to the BD relay. He was stumped at this point we halted the conversation as it was his lunch time.
4. In trying to replicate what we did earlier I attempted to bypass the relay again by jumping the coach batteries to the output side of the BD relay to give us 12v and limited 120V. Blew the 250 amp fuse I just replaced. DW is now on a 3 hour RT to get new fuses. No more jumping.
5. House batteries are down to 12.9V, I have the charger on the starter batteries. Generator running has had no effect, no life to the inverter or any effect on the electrical system. I haven't checked to see if the transfer switch on the generator side is working, it was last time I checked. Concentrating on shore power.
Not sure where the salesman switch solenoid is, unless it is the one in the battery bay. At last check there was 12v on the input side but nothing on the other. I assume this is correct if the switch is off.