Quote Originally Posted by BenBreit View Post
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And no, I was not able to get it loading from the SD Card anymore since then.
Ouch! If you don't have preboot either there is no way to recover it. Not being seen by Updater.exe and showing in Device Manager as "Portable Device" when you try to access preboot isn't proper behavior for a soft-bricked device.

I wouldn't be too hard on yourself as i think it's very likely the aera was experiencing a flash failure all along. Physical failure isn't always immediate, sometimes it seems like soft-bricking initially but the more such a device is stressed by being repeatedly flashed the worse the problem becomes. I haven't had time to examine your RGN files yet - however even if one of those has caused hard-bricking the point's moot. No preboot or SD access = no recovery method.

About the only other thing left to try is with a desktop PC instead of your Lenovo laptop, even an old low-spec'ed one with XP will do. Use only a rear USB2 port directly (no hub), not a front port nor a USB3 port. If it's still seen in Device Manager under Tragbare Geräte rather than under GARMIN-Geräte when you attempt to connect in preboot then try to format from RAW to FAT32 using Disk Management (if not recognized by RMPrepUSB).