I have now tested for continuity between all pins. There is only continuity where there should be continuity. My money is on the BM7000. I saw Die Boegener made reply to someone around datalink not working after a thunderstorm. Since I did not have my BM7000 since the beginning, I have no clue what has happened to it previuosly.
At https://archivedforum.beoworld.org/forums/p/28464/223667.aspx he replies:
…
some parts in the datalink section are dead. Nothing special, 50 cents on the pre amplifier board.
Replace:
D5= 12V zener diode 0.5W
TR1=BC547
That’s all…
Not sure if I should look into that at some point.