I got all my parts in this week to do the nav retrofit in my 325i 2005. anyway, i'm sitting in the garage now, i got all the parts installed and connected, but the screen doesn't come on when i turn the car on. everything else works. the screen even folds down when i press the arrow button, but it doesn't seem to function any other way. What could i have done wrong? I've checked cables, they seem to be all snug in their places. This is going to drive me crazy. Can anyone recommend anything? is it likely i got a bad screen? I got it from that tim fellow in germany.