My screen on my MK3 2002 went black. Following a BMW diagnostic ($125) and a $2400 offering to replace the screen unit, I bought a tested 2004 unit (with CD) and installed it...same blank. My red light is flashing on the trunk computer. Would attempting to reload the OS make any sense? Can some body give me the link to obtain the OS that would correlate with a 9/2001 build date. Thanks