Not only ECHU shows error but also this
HASHS[1 0 0] it means the first hashboard is bad.
Dumb question, but can't find the answer, which direction do they number the boards?
Looking at the back of the machine, is #0 on the far right, or left?
Why not check the mm board physically it should have something named under the ribbon cable of each board.
But my guess is if you are facing on the back the first board should start at the right and if you are facing on the front it should start from the left it just like you are reading a text beginning to the left.