The panel is wired so that the starter button only works when the ignition switch is ON. To change it so the starter button works with the ignition switch ON or OFF reverse the brown and yellow wire on the back of the panel. SAFETY NOTE: If you make this change use extreme caution when working inside the car. If you accidentally push the starter button the motor will turn over, possibly moving the car and the fan and belts will turn, in either case possibly injuring someone.
The front of the panel is sealed from dirt and moisture. If the backside of the panel will also be exposed it is advisable to seal the switches and terminals with a good silicone sealer.