Have you contacted Garmin? I have had great support from them over the years. I am aware that some very old GPS units struggle to find satellites, though the only one I have which I have given up on, is a Sony GPS from 1988, Other than that, they all still work.
Databases might be a different story. File formats change over time, and old ones sometimes don't fit into new units. I had this with my King KLX135, whose database was available only as a diskette, but King got me going.
I have the same faith in Garmin, if help is possible, they have it for you. If not, well, it's time for a newer GPS....