Welcome to the Beoworld forum !
First things to check:
- Is correct and clean voltage reaching the processor ?
- Is the reset circuit working ?
- Replace capacitors on the processor board and preferably also the small ones in the power
supply area (a 22uf and some 10uF if I remember correctly).
If these things are alright, it's most likely the processor itself that has died.
I have a BM6500 currently on the bench that does not respond to remote commands. Data is reaching the
processor from the IR interface so it could be a similar case to the OP.
As Die_Bogener mentioned earlier in this thread, not all versions of the 8032 processor will
work in the BM6500 and NOS parts are getting scarce.
I am awaiting delivery of some nice old original Siemens processors that will hopefully work.
Martin