When a fader is configured as a grandmaster, you can set the fader itself as a master or disable it. Fader size is set to 1x, and cannot be changed.
The first button is locked as a load button, and cannot be configured. The second button is disabled and cannot be configured. The third button can be configured as a blackout button or disabled. When configured as a blackout, both buttons must be pressed to set the grandmaster to blackout.