I added some music to the HDD on my 2011 CTS premium. Worked initially. Started the car 2 days later and the radio/nav screen isn’t working. The backup camera doesn’t show up, but the screen will raise as if it’s getting signal. Does anyone know how to do a hard reset of the radio? Can I reset the HDD back to factory settings. I was told I need a new screen, but not sure if that will fix the issue. Also I have no power in the USB port any longer. I’ve tried removing a couple of fuses and I disconnected the negative battery cable for 25 minutes. The screen has had a vertical line in it occasionally. The screen sometimes has no light/power and then the radio will cut off for a second. When the radio starts again the screen has the backlighting lit. PLEASE HELP!!!