how to recover from firmware upgrade?

[bimmerluv]

i have a mk4, and during the firmware upgrade (from a CD that I burned at slow speed on quality media and have used on a friend's 5 series successfully) it seemed like the mk4 crashed. the screen went blank and nothing happened. from what i recall when i used this cd on my friend's car, there was suppose to be a screen that says 'programmin update' or something like that with a progress bar. this never showed up. also, the "power" led on the MK4 went off but i can still hear the CD spinning and sounds like the laser is moving back and forth (reading?). eventually i just had to stop it. but now the nav screen is blank.

is there a way to recover from this? the Cd was v29.1. Should i try an older version?