USB connection issues on CR-10v3

I’ve given up trying to get the BLTouch working as no one seems to be able to help.

So now I need to get my original firmware back onto the printer. However, it now won’t connect to any of my laptops via USB. I’ve tried Ubuntu and Windows and none can see the printer. Creality have been totally useless other than sending me the firmware to use. Their video of the process shows v1.2.3 of their software and we are currently on 4.8.5. However, since it’s clearly a Cura clone, I’m happy to use Cura.

As no O/S I have can see the printer, what should I try next? Thanks.