I have the same problem with Nuvi 50 purchased in 2015 with lifetime map.
After the 2024.10 update, it's no longer detected by computer or Garmin Express. I tried different OS: win7, win 10, win 11. None detected it.
The USB cable is fine. I tried transfering data on a flash drive using the same USB cable.
I went to the testing page by long pressing battery icon. It shows USB DC current but USB connection not detected.
I suspect Garmin update bricked the GPS from last update.
But navigation still works.