update to Win10 wifi driver problems and screen blackout at boot - confirmed it was a corrupt Win10 OS.
How and why I don't rightly know, only used genuine software etc but my build diary recorded symptoms started after Win10 1809 cumulative update (kb4489899-kb4483452-kb4489907 Win10 1809 cumulative, .net framework 3.5 & 4.7.2 & adobe flash) which coincided with installing Logitech software for a new Anywhere wireless Mouse Dongle to be detected, and later un-installed the additional Logitech "recommended" software. Other than that no idea why but I did get can't find logiDLA.dll at boot.
Hardware all tested working after replacing with original components (I am fortunate I had replaced original RAM and NVMe from new so I could simply re-insert with internet disconnected to stop auto Win updates) and replacement Samsung NVMe drives both in good condition.
I mentioned before but will recommend again - ACRONIS True Image once again has saved my sanity and many hours of protracted OS build work. I was able to restore to a clean image with half my software installed and user.dat file intact. All back to normal - until the next "feature" update!