Having recently completed my Digifant saga I thought I would post up a few pictures. The units described in this post are Digifant II part number 037 906 022AT built by KEN in Germany. Every failed Digi II ECU that I have opened up has looked like this inside.
The two obvious symptoms of this failure are: the engine hardly runs and there is fuel in the oil.
Two things can cause this: broken engine grounds or shorting the no. 1 terminal of the coil to ground. Here is a quote from the 85-92 A2 Bentley service manual, section 8 page 20 "CAUTION- Do NOT allow terminal 1 of the ignition coil to be shorted to ground when connecting test equipment as this will cause failure of the Digifant control unit." What happens is that the circuit board becomes the primary ground path for the ignition and injectors. This is far more current than the printed circuit board can handle.
I ended up buying a re manufactured ECU from http://www.AUTOECMS.com because I couldn't find a working unit at any of my local junk yards. If you are buying a used ECU be sure to open it up. I made this mistake once and was out $200! I sent my original ECU back as a core and I am repairing the one I was stuck with.
I hope that this will help some of you avoid your own Digifant saga. Good luck!