Please note this was in our driveway and we have a video of the incident. Driver parked the car on slight hill and engaged the parking break and exited the vehicle. The car was still "On". Driver opened the door and reached in and pushed the ON button to shut down power. The brake disengaged by itself, car rolled, knocked down and almost rolled over driver. Rolled into street in oncoming traffic. Damage to door, slight injury to driver who was nearly run over.