We had some Philips Pro TVs back in the late-1990s that came with a special remote that allowed the owner, with the right up-up-left-right-up-down button presses, to bring up the Super-Secret Setup Menus. Like yours, it was possible to lock out channels, inputs, set maximum volume, program turn on and turn off times, etc. We wanted to make sure if someone "walked off" with a set then it would be totally useless!