anyone with a little more detailed help?

changed the battery on my car and the damn navi computer wont turn on.
i checked the fuses and they are all good radio works for a few minutes and then turns off. the major thing i guess is that the nav changer doesnt have the red light on wont eject the cd i tried holding it for three minutes and nothing.

is there something else i can try to get it to reboot. thanks in advance!!

its the mk 3 unit, btw.