Well I think the motor should be pretty easy to assess as with the entire length of the wires feeding your motor. With a DVOM or digital volt and ohm meter you can unplug the stepper motor at the mainboard and probe the 4p connector on the harness that leads to your suspect motor.

There are 2 sets of coils in the stepper motor assembly. And a toothed rotor on the shaft. The way stepper motors work is by energizing one set of coils which pulls the teeth on the rotor to them and then the controller energizes the other set of coils and the rotor moves to line up with that set of coils. Simple and easy operation and it all stems from this. Micro stepping is both coils energized together to create theoretical but not real in-between steps that are utterly unreliable and is why we should all chase after real steps rather than micro steps. But I am getting off topic..

With 2 coils performing the identical function within a stepper and 4 wires feeding it we can logically deduce that there needs to be 2 pairs of wires with equal resistance.

If you probe your 4p harness and find 2 pairs of wires that have identical resistance this can be taken as verification of an in-tact circuit and you should be looking at the stepper driver, or settings in your firmware or slicer for movement.
If we command greater movement than an axis can handle we might get this effect.

If you had a bad stepper motor than one of the coils should be short or open and you will not find equal resistance on 2 pairs of wires.

There are only so many ways 4 wires can be probed. And coils are stupid things that just generate magnetic fields. They do not really care about polarity you just gotta find 2 pairs logically with a DVOM. And if you can't find equal resistance on 2 pairs of wires then you should unplug the motor and test the pins at the motor itself to understand if your short or open is in the motor or in the harness between the mainboard and the stepper.

Good luck and let us know what you find.