So i assume you tried a while after battery was removed and without it re-inserted. Also you didn't mention Updater.exe but i'm sure that it didn't recognize the aera either, seeing it didn't appear in Device Manager appropriately in GARMIN Devices. However it's still 'alive' and being seen by windows albeit as a common USB flash device. You did remember to load Garmin USB Drivers didn't you? Additionally, when you put it into preboot holding the power button does the usual loading message appear on its screen? Try holding the power button first, without the battery in, and then plug the USB cable into aera's socket.

While there's life there's hope of course and i hate to admit defeat, especially on a aviation device. So i'll ponder a bit more on this until you get back to me to clarify the above queries ....