Check the cable, are you using an original Garmin cable? You need a data cable, many just provide power only.
I tried all the options. The watch is out of warranty. The cable is functional. I tried other / 2pcs / garmin 5x connection with pc is ok. One has a soft 11.00 the other 14.20. I have 15.20.
Contacts are ok. Also internal contacts in the device that connect the motherboard
I have found in the garmin forums that others are solving the problem. forums.garmin.com/.../fenix-5-not-recognized-by-pc-windows-10
Cabel is original and data cabel only.