Problem corrected it self. When the problem occurred none of functions where available like navigation, phone and using using star link. I had tried turning the car off and on 3 or 4 times. That did not correct the problem. I had also tried pressing and holding the volume button for several seconds at least 4 different times and that did not corrected the problem either. Also when I backup the car backup camera did not display.Car starts, radio comes as usual. Can not switch out of radio, can not change volume. Backup camera does not come on when backing up.