I "own" four laptops, I have two and have passed two on to a friend; two are six or seven years old and are now "reserves" for each of us, one is four years old, the other a year. I successfully upgraded three of them to W10, the newest W10 came as standard.
I've rebuilt the newer two, stepped on one (oops) and knackered the HD (rebuilt this is now my friend's primary laptop), on my newest one W10 committed digital suicide at Christmas. It's now working great again...
For some reason one of the original pair (my friend's) won't now accept updates - a particular one just hangs and has done so since late last year - and nor can I find any way to repair or reinstall W10. Looking on Google, it seems to be widespread problem which MS have not resolved. The other one works just fine.
As it should be more or less identical to my spare, plan is to swap the HDs when I have some time and see if it works; if so then copy good HD to the other. No idea if that's a workable solution...