E39 Head Unit with LCD screen
 

My '96 (USA '97) 540i has the large stereo head unit with the integral LCD screen. The screen stopped working some time ago; it occasionally shows the TV picture for less than a second, or glows green or blue. In addition to the annoyance, I can't adjust the balance or fader without it.

I took it out and examined it but could see no obvious suspects (e.g. leaking capacitors, burnt resistors or tracks), and I'm not very good without a circuit diagram, but it certainly sounds like a bad earth (ground) or other power supply issue.

Has anybody tried fixing one of these (successfully or otherwise)?

Failing that, what aftermarket alternatives are there now?