Sounds stupid but is there any way to turn off the navigation by the press of a button?? Thanks

 

Yea, you should see a option for "setup" in the bottom right. click it adn you will see i think it says display. well it will have 4 options "off" "day" "night" and "auto" just click the "off" and to turn it on just click one of the buttons on the right like menu or ac. hope that helps