Tony, I don't know if this is going to be of use? Here goes anyway.
I assume you have a reasonable knowledge of circuits based on your previous posts?
The failed panel is basically a low current switching panel. It also functions as a monitor for various systems such as water levels, battery volts etc?
The high current switching (power to a circuit) is triggered by a low current sent to the main board (power board) via a bank of relays (what we used to call contactors). The trigger energises a relay coil to close (or open) the high current contacts on the main board. This switches the high current circuit on (or off).
In theory you could trace back the trigger line following the positive from the power board? Not something I would want to do!!!
However, In the first month we had our new 37 cruiser one of the relays became erratic (the fridge). Immediately I suspected the fridge thermostat, because they really are a source of frustration. But, checking out the relays we found one was working only when there was a z in the month and battery volts were 13.5v or above. However the panel indicated I was; on , off, not working, Kaput!
Swapping out the relay solved the problem.
I guess you could look at all the components on the board and check the values, including the IC's ? A Google search on each item and its number may give you the various vales?
Not sure this is a lot of help but hey ho.
Good luck with Bavaria, Etc. if you get any info pass it on. Bavaria seem to think they are selling cars not boats, and as such we have to wait for Haynes to bring out a manual
Best regards.
Ant.