BarryLawnmower

Hi all I have recently purchased a 2006 BMW X3 Jap import that has had the factory radio replaced with a JVC radio, my vehicle is fitted with a screen on the dash that still goes up and down but the screen is just blank and I'm wanting to get it working I'm hoping somebody might be able to point me in the right direction, would I have to install a factory radio for it to show or could it be an issue with the GPS unit in the boot? Any help would be appreciated ☺️