The head unit itself has no display but the only function it has is that it plays, changes, and ejects CDs. The other control bottons on the steering wheel and head unit itself have no function when pushed or toggled. I tried disconnecting the battery again today and had no change in statis. I can't get the DVD to eject the NAV disk. I have read in forums that the NAV disk is part of the Boot up operation when turning on the car, how true this is, is anyones guess. This is the second Head Unit in this car, the first unit had multiple problems reading the NAV discs after several years.