I have a 2007 Q7. The navigation system does not work as of yesterday. I have 0 satellites. The navigation system starts to calculate the miles and the arrow comes up and then the map goes blank (all white). I took it to the mechanic and he did a computer test. The error was 862 - antenna not connected. I just had a new bumper installed by the same mechanic and he said that has nothing to do with it. Any suggestions?