This is sort of a shot in the dark, but if you can disconnect the power to the unit for 30 seconds or so, when you reconnect it the unit might go through a reset process and clear up the confused state the changer is in. You can try disconnecting the fuses. Look at the fuse panel for them, there might be more than one. The other way to do this would be to disconnect the battery (only one cable) for about 30 seconds. I don't know that this will help you, but it has worked in my car.