Can`t believe that you are giving up!
Took some hours to figure out what the issue is. Now we have it (I think!) and we nearly solve it.....
Did you really switch your Beolab to ML?
Press MENU - MENU -(twice) - 0 - 2 - GO (service menu, should be MCL or something like that displayed) - arrow up (to change to ML -
display shows ML..?) and GO (or STORE) again.
SW update here in Euroland is about 40-50 Euros for the eprom and maybe half an hour work.
Good luck.
Stefan