I know this is an old post, but I just came across this trouble shoot for Power FC. Perhaps beneficial to future Power FC user as well.
The PowerFC manual states to start the car, ensure no errors are present and let the car idle for at least 30 minutes. During this idle period wait about 10 minutes, turn on the air con, wait another 10, turn on the demister, wait another 10 minutes or so and then your car is ready to drive. If you short cut the self learn idle procedure once the car is turned off and back on again it will simply stall each time. If this occurs you must factory reset it again and do the procedure from the start