1) turn on ignition, but don't start the car.
2) press and *hold* the APPS button on the radio while performing step 3 below.
3) cycle the head lights 3 times (turn on then off the headlights 3 times)
- this activates a hidden service screen on the display, you can release the APPS button
4) press and hold the "INIT" button on the display until a dialog box appears with the text "Personalized data is initialized. OK? [YES] [NO]"
5) select YES, and your radio returns to the factory settings