Well regardless, the point is it's not soft-bricked so it means the problem is likely a more difficult hardware failure - a failing component on the PCB is my best guess.

That can be lived with (provided the USB socket still allows it to charge) because you can add, overwrite or delete files and even complete folders using SD commands. Read this thread for how to do that: [Only registered and activated users can see links. ]. You can obtain updates of maps and other files from GarminExpress by using the device's GarminDevice.xml in a Garmin folder on a thumb drive or media card to make a clone of your device.