There are a few possible causes. If with the motors disabled you find resistance, means there is a problem most likely on the mechanics. Check there are no debris on the rails, the long Y belts are not over-tensioned and the rear shaft (the one that transmits the movement from the Y motor to the carriages) is not bent because of the short belt tension. I suppose instructions on how to tension/release the belts are available on the BCN3D website.
You can guess roughly where the problem is depending on whether you find resistance in one specific spot along the rail or if it repeats periodically (and so it has something to do with the pulleys).
It’s worth always excluding problems with the mechanics before messing about with the electronics.
Let us know if you solve it.