Clearly they don't want anybody having access to the menu.
Setup is done SOLELY with a SPECIAL remote and/or USB cloning.
The Manual states:
ACCESSING THE SETUP MENU:
To access and adjust the setup functions, YOU MUST USE A
SPECIAL SETUP REMOTE CONTROL (not provided with the
TV) IN THE RC5 SETUP MODE. All the following instructions
assume the use of a setup remote control in the RC5 Setup
mode.
If you have the TV, open it to see if hidden service buttons are inside.
Martin