Yes, I have had this happen 2 times.. Not sure exactly what causes it, but it seems to be a design issue. When the battery is low and you put a jumper on the battery or if you replace the battery, a voltage spike occurs when connecting the new battery can sometimes short out the navigation computer in the rear trunk on the left compartment. This provides the video signal for all BC functions to the navigation display in the front. .. I assuming you can still hear your radio and change stations using the front display, but cannot see the display? correct? The easiest way to check if its bad is to make sure the battery is fully charged and swap it with a known good part from another vehicle. Ususally you will have to replace the unit and recode the vehicle. As for your keys, they need to be reprogrammed to the vehicle. they probably lost programming when the voltage went low.