Microbit no longer talks to its USB port

I have a Microbit that no longer responds to the the USB, and I think the reset button.

The last Micropython program (radio strength detector) still works (but I am unable to change it - if it had been the beacon program that would not have been an issue).

I have tried it plugged in to a Windows 10 laptop and a Raspberry Pi (and checked the cables are sync not power with another microbit and a Circuit Playground device).

Has anyone else experienced a similar issue?

Any suggestions or is it a write off?

Thanks in advance.