Recently picked up this X5 with a stereo issue - screen was busted on the old small screen tape deck, so I picked up a widescreen monitor. Monitor powers on but screen is still blank, and music will play but cuts off after a few minutes. DSP system BTW.

After reading a lot about these systems it seems the next step is to check the nav unit. What's in the car is part #65906908311, MK II according to real OEM. Sounds like the MK IV units are the best, but I really just prefer the most affordable solution at this point. Any way to test or repair the unit myself? Anything else I should check prior to replacing?

Will an MK I work, MK III? Are all of these units interchangeable? There also seem to be numerous part #s for each MK unit, will all work with this system or only a select few?