If the Belt breaks, the Centrifugal Switch on the Motor disconnects the L2 power to the Heater (unless the Heater is partially shorted to the cabinet ground, as Repair-man mentioned).
so...it could be a broken Belt and/OR (most likely) the Thermal Fuse causing the Motor not to run, but either way, the Heater is partially shorted to the cabinet ground, causing excesive heat because the blower isn't working, blowing the Thermal Fuse.