If it was me, I would just replace the drive motor assy (including the brakes) in that side. these motors and brake assy do not last all that long in the best of conditions.
I think it is not correct to say that with the unit not moving that "there would be no voltage at the wheel drive motor". The motor is still connected via the controller and if it or the brakes had an open circuit, the controller would notice and shut down, so there must be some continual complete circuit to the drive motor and brakes.
Why there is enough power to create smoke is a slightly different question.