CS-D508, stepper not rotating and ProTuner throws "Unknown Device"

Hi!
Got two problems with a CS-D508 I just bougth.
1: I connected this drive to a AP8918L9504-E stepper and a 48v PSU. No mather how I configure microsteps etc, when I try to get it to rotate (DIR/PUL mode) it moves ~1 step and when the pulses stop it bounces back that ~1 step and eventually throws a position following error.
2: Trying to connect to it with ProTuner I only get "unknown device" message. Tried motherboard serial port and several USB2serial cables and two different PC's (win10 and winXP)

Any suggestions?