It looks like it doesn't have enough power.
You could try to switch 2 stepperdrivers, but make sure to put them back the right way.
Look at the potmeters (tiny screws, only on 1 side) for an indication before you take them out.
The stepperdrivers are the small chips connected to your electronic board on the bottom.
The E stepperdriver is the one that is alone, like not in the row of 3.
If that doesn't make a difference, look in your UltiController.
If you have an UltiController, go to UltiController > Control > Motion.
I don't know from the top of my head what it is called, but what are the values that are connected to 'E' ?
If it turns initially then possibly the Pololu driver is over heating
Have a look at it and see if the heat sink has come off or the fan underneath is not spinning.
After that look up in the wiki how to adjust the trimpot on the Pololu driver
Link to post
Share on other sites