Thanks KiwiJochen for your suggestions.

I have managed to bring back most of the failed components, except that the steering wheel buttons still does not work. And I cannot clear the error on the SMG gearbox...tried to clear it with Ediabas / INPA but it keeps coming back when I start the car...So it seems like a visit to the dealer is imminent...

On the bright side, the navi module is working great, it's so much faster navigating through the menus now. And it doesn't say "no disc" every 5 minutes anymore

BTW...if there's somebody out there who feels the urge to try to interpret the errors I have gotten from INPA, please be my guest.
I have it as a PDF...I've tried to make some sense out of them...but I don't know enough about these things.

Regards

Tommy