If the unit has 2 completely separate "modes" (radio/navi), then sometimes it will just keep showing the navi exit screen in "navi" mode when exiting (usually, they disable the exit function completely). After exiting the nav app, if you press the physical "Navi" button, does it take you back to the radio mode? Also, on my 2DIN, if I exit the navigation app, I can just press in the middle of the screen to restart it. But, I don't think it's supposed to do anything different when exiting navigation since that navigation app is usually completely isolated in it's own OS. It's like there is 2 instances of the OS running - one for navigation and one for everything else - and you use the "Navi" button to switch between them.

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