Hi I am new to the forum I have recently bought a second hand Kenwood car stereo with built in Garmin navigation, it is a discontinued item and can't find no update for nav on Garmin website! I have read about linking it to a laptop and changing some files ( gmapsupp.img and gmapprom.img) to a newer update but unsure how to go about it? The model of the unit is Kenwood DNX7250DAB if that helps I maybe shooting in the dark here as unsure how to update so hoping you guys can point me in right direction, I have attached few photos of model and info when I go in settings on unit