Pull the HEVAC unit out (it's a few trim panels and screws etc)
Unplug the blend motor connector from the HEVAC controller, and then find the Brown/Black wires from the blend motor with the BLUE tape on the wire (assuming they are still color coded!)
With a couple of thin bits of wire to poke in the end of the connector, and a 9V battery (or 12V power source) connect the battery up and it should move the motor. Swapping the polarity will make the motor run in each direction - so just manually drive it until it's at the other end of it's travel, and it should be at full hot.
If you want to make sure the HEVAC won't try to drive it again, then either cut one of the wires, so it can't try to drive the motor - or pop the pins out of the connector housing by lifting the rear locking tab on the housing, and then using a small jewellers screwdriver, or a needle etc in on top of the pin from the front to lift the locking tab on the pin itself, and then pull the wire out the back of the connector.
Replug the connector to HEVAC and refit.... warm air should be the result until you can get around to changing the blend motor.