If it's being supplied with water and not spinning it can only be 1 of 3 things.
The arm is split along it's seam and is opening under pressure.
The end holes are blocked (this is what propels the arm).
The arm is physically jammed by something hanging from the basket.
If it's only being supplied with a little water then it would suggest the alternating valve in the heater isn't working and has stuck partially open to the top arm and near full open to the lower arm.
When it's working you should be able to hear it change over from bottom to top basket and back again.
The machine washes 1 minute on the bottom, 55 seconds on the top and the changeover lasts 5 seconds.
Basically you should hear the swish from the lower arm, then a lesser noise as it changes then a swish from the upper arm.
Test the machine again, see what you find.
Let me know.