@BenBriet
Apologies for being unavailable for so long.

From your PM:
...... I think it got hard-bricked now. I am not able to start the device with power button anymore. If I connect it to the wallcharger, it is in a continuous boot-loop with basically just a black screen and the buttons on the lower part just light up, go off again and so on.

Nevertheless: If I connect it to my laptop indeed you can hear every 10seconds the usb-sound AND in device manager I can see it (but not as Garmin Device though) connecting and disconnecting. Its creating two drives, garmin flash and garmin storage. After leaving it for a while it just stops bootloping and you can see both devices as functional in device manager, but I can't access them on windows explorer, with cure3 or with RMPrep.

So I am afraid its really lost now. Yesterday morning I tried another rgn-file with cure3, and I guess something went wrong there. Anyway just for you as an update. I hope its not too confusing what I am writing. We can continue the discussion in the topic, of course. My last hopes are dying as we would need the gps on a flight for Saturday. Of course Garmin stopped the repair service for the aera in July.
Well that's not good. Need some more info though before we admit defeat because while it still turns on there's still some hope for a miracle. Possibly it's got flash damage however and if so no software solution is possible.... However, let's assume it's only badly soft-bricked for now. Need to know a few things:
  • What does it show as in Device Manager when it stops bootlooping? Screenshot would be good.
  • Please post a copy of the RGN you used with Cure3 before it bricked even more.
  • Does it still read commands from SD card?