The Red Button trips the circuit breaker and the Black is the reset. The black one is on the side and the red one on top. If you press Reverse with the Parking Brake set it will trip right away. Don't ask how I know.
i will add my big old dumb butt to the list of folks who discover that the reverse wont run long with the brake on. as they said, reset the breaker under the right side cover.
Not sure what year HD moved the reverse motor reset. But on the 2009 and 2010 the reset is located under seat on top of reverse motor. OP didn't say which model year he is riding.
The reset is under the right side panel. Found that out last night when I had the parking brake on and tried to back out of the garage. Push the little black switch in and you'll here it click. You'll be good to go.