Hi @LElers
The first thing I’d do is take LightBurn and USB out of the equation.
Power the Gweike off, disconnect the controller USB cable from the computer, then power the machine back on. Does the Z axis still try to drive beyond its home position or crash toward the bed?
If it does, that points to a machine/Z homing or sensing problem rather than LightBurn.
For LightBurn, I’d also go back to the Ruida 644xg device profile rather than 6640_Y-Cloud. The Gweike setup should have Enable Z and Optimize Z Moves enabled, with Relative Z Moves disabled:
https://forum.lightburnsoftware.com/t/how-to-use-gweike-cloud-with-lightburn-tips-tricks-faq/97874
Let us know what the Z does with the USB completely disconnected.