Why can't I access the enhanced service menu?

[Plenz]

I succeeded to build a remote control with an Arduino Nano and tried to enter the enhanced service menu in my UE32D5700.

I pressed INFO - MENU - MUTE - POWER and the service menu appeared.

Then I pressed INFO - FACTORY. The service menu disappeared and on the top of the screen appeared a red text:
T-MST5DEUC-1016.0 0:02:27 32A6UF0E EXT
That was all.

Then I pressed FACTORY - 3SPEED and a message box appeared "not available" (translated from German).

Seems that the previous owner upgraded the firmware (now 001016) and I should try to downgrade it, right?