"Software Loading" usually only appears when it's being flashed. "Loading" may or may not appear briefly before it enters calibration mode however. The actual on-screen message or lack of it is device-dependent when in pre-boot mode. Preboot mode is available only for the time from it powering on up to the white calibration screen appearing, old devices were 30 to 60 seconds, modern devices can be annoyingly fleetingly short. Once a data packet is received from Updater.exe it will hold preboot and show "Software Loading". If nothing is received it drops preboot and goes to calibration.

It notable that many devices on entering preboot will immediately show "System", or "Loader" while other types will just freeze on the Garmin Logo screen with nothing else on-screen to indicate they are in preboot.

However if it also cannot be recognised in MSM i.e. Mass Storage Mode or MTP i.e. Media Transfer Mode then it indeed has a hardware fault. Please state specifically whether it can or not be seen by PC normally, after you've read the rest of this post

If you CAN see it in MSM or MTP but NOT in preboot then check the following:
  • Load (or re-load) Garmin USB Drivers: [Only registered and activated users can see links. ]. The specific USB drivers are essential for preboot but not for MSM/MTP connection.
  • Try a different computer, some laptops can be flaky with Garmin Mode and preboot mode devices. Use a Windows desktop PC, even an old slow one with XP will do provided USB drivers are on it.
  • Use only a REAR port on the PC, USB2 direct on motherboard only. Avoid using a front port, a USB3 port and definitely no hub or add-on card port.
  • Put the device in MSM as per [Only registered and activated users can see links. ] before attempting preboot.

If after doing all the above it's still not showing up in Device Manager in preboot, or if it in fact can't even be seen in MSM/MTP then it's certainly got a hardware fault.

Although as said in Post #3, a device without any data connections via USB can still be updated with GarminExpress using an SD card/flash drive to mimic the device, if such a device ever 'bricks' due to a corrupt file it likely won't be recoverable. Because most soft-bricked devices don't boot far enough to see an inserted card, they can only be recovered using Cure firmware loaded via [Only registered and activated users can see links. ] in preboot (Updater.exe can't be used in MSM and GarminExpress can't be used in preboot).