@Chris Annin Is the J2 ENGINE defective? He's not moving.It makes a vibrating sound.Does it make sense for me to order a new model YGS50 model?video link:https://youtube.com/shorts/cl5YI1DHuvs?feature=share
I agree with Chris. It's about wiring power cables. Check that A+A-B+B- wires which go to J2 motor.
I cant hear it vey well but the movement looks very much like one of the power wires to the driver is incorrect. I would double check the A+A-B+B- wires and make sure they are exactly as the schematic shows - I suspect one of them is off.