If it is variable speed and soft start, it may have a digital speed control that could be fried? Repair may not be easy and replacement circuit board could be pricey. If you open it up, inspect the circuit boards closely for any signs of charred or melted components.
EDIT to add: also look for a fuse on any of the boards. Sometimes they have a fuse soldered to the board to protect sensitive components on top of the thermal fuse that protects the motor for overloading.
--Nathan, TX. Hire the lazy man. He may not do as much work but that's because he will find a better way.