well that sucks.  but  lets think it over.

controller

V
V  cable
V

slot 0
slot 1
slot 2

so  swapping the bridge did nothing.

this means

A) all bridges are good and some other thing is bad.

B) all bridges are bad and everything else is good.

What can we do on my end?  I have 8 working m10's with 1 bad board . Board is tested and does not work on any  of the 8 units.

but all 8 units can run all 3 boards.  as I have done lots of swapping.

If you send me 2 bridges and I swap them in and they work we then know the bridges are good.

Still leaves cable and or controller.

I have an un programmed controller which means if i send it to you  you need to go to telegram and have yang help you program it.

How about this send me 2 bridges I will drive up to clifton and test them.  I they work I will send one back and hold one as a spare.
I can also send you the unprogrammed controller yang will help you program it.

If it works  we know the old controller is bad.

If it does not work  we are stuck on cable or replacement controller.

maybe I can find an 11 x 2 pin cable    as it is easier to first test it.