@fredallas True, but that can be problematical. Yesterday I set about installing ZoinOS and downloaded the file. Then went to Balena Etcher (as recommended in the installation guide) to flash that to a USB stick (brand new, opened the packaging to do it), and was unable to do so: the flash started then stopped after about a minute with a W10 error message about unrecognised system or some such (presumably relating to Balena?). Tried it a couple more times but the laptop now fails to recognise or open the (empty) USB stick as my D:/ drive.
Right now !'m not sure what to do: I've written it up and my son is goint to check it with one of his tutors and college and a couple of friends whose parents are IT developers over this Bank Holiday weekend, so we'll see what comes from that. Decidedly pissed because I've spent the past 12 months building up to this!!!!