Hi Kim, unfortunately it sounds like the controller has definitely died.
I think it will be at least two of the six
MOSFETs (possibly more) that have failed in a short circuit state, but it is difficult to say whether more electronic components may have also sustained damage within the controller.
If you
remove the controller and disconnect the three thick Phase wires going to the motor, you should find that the wheel will turn easily again, as the resistance is purely due to the Electromagnetic Dynamic Braking effect caused by the shorted
MOSFETs.
Unfortunately, the controller's circuit boards are potted in a silicone gel type compound which makes it very difficult to dismantle the controller to allow failed components to be replaced:
The
MOSFETs are the six black square objects mounted on the underside of the outermost circuit board:
Unfortunately, I don't think that you will be able to successfully access and replace the damaged components, so you will probably need to replace the complete controller assembly.
Alan