Z axis stopped moving

Z Axis over traveled and will not move. How can I test it to see where the malfunction is.
Need troubleshooting instructions. You Tube suggestions would be awesome.

Thanks,

Ramiro Schuur

Do you have a z axis homing switch? Maybe you need to manually back it off until the switch opens. I’d unplug the motor when doing that as a current is generated when you turn the motor manually.