My Nuvi 2557LMT (bike) and 2598 LMT (car) both told me they were due for updates. So I brought them in, plugged them into my PC, opened Express + it wiped the maps on both units. Now neither will function. They show the road, but the icon drives off both sides of the road and the map appears to have lost all detail. It does show speed and direction. I've tried uninstalling + reinstalling Express. I've tried doing factory resets on both gps. When I tried to do the map update, both units showed "error installing update". When I tried to update the map on the pc only, the installation completed successfully. So, it wiped out two perfectly good gps, now what?