Are you able to reload Garmin Maps. if so do a format then reload Garmin Maps on device with product key then do updates (software and map) This I've had to do my self at times.....it works for me.
You can do all this through the Garmin website. Garmin will ask for some information from your device to find out if it's valid for map updates or reloading maps back onto your device. Q.. is it registered with Garmin ..if so just log in to my Garmin..