Check if the Z-axis motor cable is loose, if the cable is broken and squeezed, and unplug the cable and plug it in again.
①Check whether the motor interface pins are bent or broken.
②In the case of shutdown, manually rotate the motor screw to confirm whether there is a jam. If there is a jam, it is the problem of the anti-backlash module or the motor.
③Remove the coupling, turn on the machine to move the Z-axis, and observe whether the Z-axis is stuck. If there is a stuck, it means that it is a motor problem. Otherwise, it is a problem with the anti-backlash module.
The above methods can not be solved, it may be a motherboard problem, please send the final results of the investigation to the aftermarket engineers.
Replacing the motherboard video link: