Arduino M0 "USB Device Not Recognised" (Two years ago, it is still encountered )

Hi,
(This is a problem of Alex two years ago, still encountered today, the problem has not been solved so far)
I am having trouble getting the native USB port of the arduino M0 (Not the Pro, mine only has one USB port). Once I connect the arduino to the PC I get the message USB Device Not Recognised.

I am using Arduino IDE 1.8.13 downloaded from Arduino.cc. The M0 is board model R3.
The installation of the IDE and all drivers went OK as far as I can tell. I have installed the SAMD board library and selected M0 as my board.

In the Device Manager, the board appears under USB as an unknown device.
On reset, the 'L' led flashes rapidly, then once per second. Also, the USB port disconnects, then reconnects with the same message.

I have:

  • Tried under Win 7 64bit and get the same behaviour.
  • I have tried 3 different USB cables of different make and quality. These all transfer data OK when used with my phone.
  • Pressing the reset button repeatedly.
  • Read all of the troubleshooting guide on here: https://www.arduino.cc/en/Guide/Troubleshooting
  • Installed the adafruit drivers package, just in case.
  • Verbose upload, pressing the reset button when the com ports are scanned.
  • Disabling driver signature enforcement.

Any help much appreciated.

Thanks,
Kmimax

(mod edit)

arduino-m0-flat.jpg

arduino-m0-flat.jpg