Hi,
We can close this... I really was too stupid.
Instead of pressing the actuak Eject Button (inside, with open front) i pressed the one outside, which opens the front.
Just when i figured that out and went to the car to try again the update worked, without the need to go to test mode - miracles happen .
By the way, on my HD3 the update worked fine, all languages (in my case German) are still there and the Radio and Traffic information (RDS and TMC whoch are different in the Z2) are still working fine.
Freezing is also gone, as far as I have seen. Thanks to this forum!