The unit lost all satellites. Now will pick up 5 weak signal and shows GPS error 90 ish feet. Contacted customer support. They said reset factory settings and leave unit with clear view of the sky for 30 mins. I had tried that but did it again. None of my marks or waypoints were lost. Now picks up 6 weak signals and shows GPS error 50 feet. Contacted support again, told to update firmware (currently have 3.8) I've downloaded the update 4.1 to an SD card but the Garmin is not finding the file. It detects the card but no files. Can someone tell me if I'm doing something wrong with the update please.