This may be a stupid question (and ignore me if it is!!) but are you using the manual for the Mk1 Beocom 6000, only I have had a problem in the past that the user manuals on the B&O site are the newest ones and looking at the one for the Beocom 6000 that is for the newest one!
To get the MENU on a MK1 you need to press the black dot between the A & V then 7 (MENU). I do have a PDF version of the MK1 manual if you need it.
Please ignore me if you have tried all that :o)
Stoobie