The RVU display should tell a lot. One last shot on the doors....on the SPU Link Board, lower left hand corner is that double push toggle switch. First push takes the car out of the group (single flash red), second push disconnects doors (double flash) or maybe it’s the opposite. Whereas the “DOOR I/O” knob removes door power IIRC. Just trying to eliminate the small things. I think it’s Error 104 for “DZ not on when expected”.

Hope you get it figured out soon.