Press the ON, OFF (or ON/OFF) button to switch the projector ON or OFF. The button will flash to indicate it is warming up/cooling down. The projector will beep(on=once, off=twice) and prevent you from selecting other buttons until it is ready.
PC 1 and PC 2 (or Laptop, or Doc Cam) buttons select the Main PC and Visualiser/Laptop connection if they don’t have separate control buttons.