Before switching on the electronics for the first time

Set to 5V output on D3 DC-DC step down

Option 1

You put 12v between IN and GND
With a multimeter you measure VO and GND
Turn the potentiometer until you measure 5V

Option 2

Cut the jumper on ADJ
Put a drop of tin on the 5V jumper

Adjust the reference voltage of the stepper drive

You have to adjust it to supply 1A to the motor, this way the motor will hardly heat up and it will have enough power.

Turn off the electronics
Disconnect the motor
Turn on the electronics
Stop from the web interface so that the hotend is not heating up
Measure the voltage between the small potentiometer on the driver and ground
Turn the potentiometer until you measure is about 0.4V (0.4*2.5=1A)
Once adjusted, turn off the electronics
Connect the motor
Turn on the electronics again

Never connect/disconnect the motor with the electronic on