This is an easy fix.
Once the radio has had the wrong code entered 3 times, it locks itself and the display will read "OFF". This is really just a nuisance to a radio theft and does not require any special tools/equipment to unlock.
To unlock the radio back to"CODE" status, do the following:
Turn the ignition key on.
Turn all accessories off (AC, Headlights, anything that will drain the battery)
Turn the radio on so that i displays "OFF"
Wait approximately 60 minutes. Some radios unlock in as little as 45, some in as long as 90 minutes... The average is about 60 minutes though.
After the 60 minutes (roughly) the display will go off on the radio. The next time you turn the radio on, it will display "CODE" again and you can re-enter the correct code.
Be sure your battery is up to the task of having the key on that long. If in doubt, either put the car on a charger if available, or have the car running (take a nice long drive). Just be certain you do not cycle the key until the radio has completed the unlock process or you will start the timer over again.
If you have any issue with the other code, I would be happy to verify your code for you, but would first need some information from the top of the radio. Just let me know if you need that assistance as well.
Edited by Doug C on 6/2/2010 at 2:28 AM EST