I am fairly positive that I have used SHIFT 90258 on all versions. I don't know any other way of engaging "Test mode" so I must have.
I must confess to always using a Beolink 1000 as I never had much success with a Beo4!
The Beosound 9000 must be in STDBY and if you have no speakers connected you must select Option 1. The remote must be in AUDIO so select CD on the remote.
So the routine is :-
CD, STDBY,SOUND,1,STORE,SHIFT 90258 should get the display reading TEST MODE ON
I have also found it more difficult to achieve TEST MODE ON after the glass door was removed!!
Just my observations!!