If it's the same as my P6400, then push the "6" button once when the unit is OFF and the car is ON.
The "5" button controls the 10 second Normal/Reverse image mode, the "6" button controls Demo mode.
You should hear a small beep when you push the button.
1999 Buick Park Ave Ultra
Head Unit: JVC KWHDR720
EQ: Audiocontrol EQL
Front Stage: Hybrid Audio Technologies Imagine 5.25 mids, Morel Maximo tweets
Sub Stage: Boston G3 10", 0.5 cu ft sealed
Amp: PPI Phantom 900.4
Rear Fill: Boston SE953 6X9's