It's normal that a Garmin device connected to a PC when it's in preboot will not show up as a drive in Windows Explorer. That's because it's not in Mass Storage Mode. It will also not be detected in Disk Management as a Garmin Device and in Device Manager it will only show up under 'GARMIN Devices' as 'Garmin USB GPS'. When it shows there it's certainly in preboot and will be recognized by Updater.exe and can be flashed.

[Only registered and activated users can see links. ]


When preboot period expires or you remove pressure from the top LH corner of the screen, a healthy device will disconnect and then re-connects in Mass Storage Mode provided the USB connection is maintained. Once in MSM, it's visible normally in Windows Explorer, Disk Management and again in Device Manager but this time under Disk Drives.

[Only registered and activated users can see links. ]


However, your device is not healthy. Because it's bricked it can't default to MSM. It's by loading Cure firmware that we enable MSM to allow a re-format with RMPrepUSB.

Summing up: You can get it to enter preboot, load Cure3 firmware to Updater.exe but it drops out of preboot or loses the USB connection before the flash completes.

Please post a picture of the error screen displayed by Updater.exe.