biododge1

my navigation stopped working on my car. the batt went dead, so i jumped it-now i have no info at all on the dash monitor. the screen is working but it's like its on the "wrong channel"-flickering. everything worked fine until the jump.
I have heard that after a jump the os software can be wiped out, and needs to have a reboot disk installed.the dealer today tells me that the unit is fried, and can't establish communication with it. I don't really believe this as the unit will receive-eject-and try to read a disk. and he never mentioned anything about even trying to reboot the system.
the nav unit is a markII 2001 7 series bmw.

am i on the right track here? or is dealer telling the truth-I don't want to shell out 3k for a unit if i don't need to
thanks