Operation Wolf "Trunk" Button

[dcsportsfan]

I just bought an Operation Wolf and in the middle of cleaning it up and found a button inside the cabinet beside the volume adjuster named "Trunk". I assume it is some kind of service button do the best of my knowledge after reading the schematics, but when I push the button noting happens. I have done a little research online and came up with nothing. Does anyone know what this does or how to put it in service mode, and lastly is there anything worth getting into if I get into the menu?

Thanks in advance...