Thanks for the reply and the links! It looks like you are working through many of the same issues on your two 2010 S's that I am having with my DS (including the motor temp sensor).
I am by no means an electrical expert, but I will try to explain things as I understand them.
As far as I have been able to determine, the BMS units used in the 48 volt Zeros simply close a circuit within the MBB when things are as they should be (no error codes). In the event that the BMS senses an issue, the circiut remains open (similar to when the kickstand is down), the MBB displays a generic BMS code, and the MBB will not trigger the contactor. I suspect there is no CAN communication between the MBB and the BMS. This lack of CAN communication may be the reason why the BMS uses its own beep trouble codes.
My 2009 X used the same BMS, as the DS does, and in that case the BMS strictly acted to complete the contactor circuit. Only it didn't do this successfully because it was so very fried and crispy.
To bypass the BMS, on the DS, I simply ran a jumper wire between the brown and black wires on the six pin BMS connector (I by no means endorse this) and the MBB was happy enough for me to go for a test ride.
Thanks for suggesting putty, I will look into trying it. If I remember right the saying goes perturb and observe.