Just checked, and somewhat to my surprise, I don't have it! The 8002 one is there which is essentially the same machine. However there is no menu for deciphering error messages. The normal fault with these machines is due to faulty capacitors and then the tacho disc. I would suggest chatting to Dillen (Martin Olsen) who has remade the tacho disc and also knows all about capacitors!

Sorry to be of no real help. 

How can I reach him?

regards

I have sent him a PM for you.

As far as I'm concerned, there are no actual "error messages" as we normally know them, only weird readouts and no manuals will explain.

In your case, it would make sense to check if all PCB board connectors are correctly mounted (reseat all) and if the CPU actually runs.
If you are not into electronics, this is not a task for you but, as Peter suggests, aging capacitors can cause the strangest faults and would be the first thing to replace (a kit is available). Also check for bad solders in the power supply area and around the PCB edges where the connectors are.
I normally suck out the old solder and use new solder with a hint of silver in it when resoldering to avoid future cracking.
The CPU itself is very robust, they hardly ever fail.
If the tachodisc is of the old photographic type I suggest you replace with a stainless steel one but even with a damaged tachodisc the Beogram would still rotate the platter albeit unstable so is not the reason for the strange readout.

If you have any other symptoms, reactions to buttons, platter and arm movements, please let us know.

Martin