From the Owners Manual
"If your vehicle’s battery is disconnected or goes dead, the audio system will disable itself. If this happens, you will see ‘‘CODE’’ in the frequency display the next time you turn on the system. Use the preset buttons (icons on vehicles with
navigation system) to enter the fivedigit code. The code is on the radio code card included in your owner’s manual kit. When it is entered correctly, the radio will start playing. If you make a mistake entering the code, do not start over; complete the five-digit sequence, then enter the correct code. You have 10 tries to
enter the correct code. If you are unsuccessful in 10 attempts, you must then leave the system on for 1 hour before trying again. If the code card is lost, a dealer can access your code with your radio’s serial number. To access the serial number, turn the radio on. It must display ‘‘CODE’’, then turn the radio off. Push the preset 1, preset 6, and power buttons at the same time, then quickly release.
You will have to store your favorite stations on each side of the preset buttons (1 6) after the system begins working. Your original settings were lost when power was disconnected."
You can power off the system by pulling the #7 (10A) fuse in the under-dash box and start over again. If the power was off long enough it may take some time for the GPS system to initialize.