If this is not a CIB (control in a box machine), you should have a AUXBOB board on the bottom of the cabinet. It has only one green connector. Pull it and it removes 12VDC from the drives and enables them. One drive will have the RED LED ON. This is the axis that has the fault. Swap the drives (turn machine off first) and see if the fault follows the drive board (fault is the board) or stays with the same slot (fault can be motor or cable).