My Nav screen is not working either. Interestingly, it was working when I test drove the car before buying it, but days later when I went back to make an offer, it wasn't working. They made a good enough adjustment to their asking price for me to go ahead and buy it figuring being experienced installing electronics that I could probably repair or replace it without costing too much. Astrobuf, if it's a bad screen, where can I get the part for $100 you mentioned? Or, would it be easier just to buy a used complete nav unit online or would security codes make the problematic?