The nav option says CD error and dvd won't come out.

"I have seen this happen once on a cassette tape deck. There was absolutely nothing you could do to make the deck eject the cassette.

Try resetting the power to the unit by disconnecting the vehicle’s negative battery cable for a few minutes to an hour or do the computer reset process. When you reconnect the battery and turn the car on, it may eject the disc or the nav unit may begin to work properly again."