Ask around on Bimmerboard.com as well for any E39/E39 owners in your part of the world to help you.

Honestly, the quickest easiest way to test is to fit the units in a known working vehicle.

If you are not familiar with oscilloscopes and the correct waveforms for video signals then you will struggle to understand what you are seeing, and you will struggle to drive the oscilloscope

Keep hunting for a friendly BMW forum member within your town or within a couple of hours drive from your town.