@at217

When you see on nuvi screen system and loading then you in pre boot and if you have updater.exe open and installed garmin usb drivers then you will see that your unit is recognized

If you folow tutorial from smokefree you will see your unit in updater.exe window.

This garmin driver you MUST install and updater.exe will see your device:

Spoiler: Usb drivers
https://www8.garmin.com/support/download_details.jsp?id=591