Upon a successful upgrade, you may be issued a new Windows 10 product key. View your key using a freeware utility like Magic Jelly Bean Key Finder and try using that for the install. Keep your Windows 8.1 product key at hand, just in case.
Ok well windows is now fully installed and working great! Been using it for a few days now and I find it fantastic. Boots up in less than 10 seconds..........
That's if I can get it to boot up at all first!!!!
Before the upgrade I never had an issue with my laptop. I'd press the power button and within 20 seconds or so i'd be on the desktop. Now when I press the power button the laptop turns on but the screen stays blank. The hard drive doesn't do anything and it just stays like that. It does it multiple times before the screen eventually comes on and the hard drive kicks in and boots up.
What I have noticed though is I can try and try again to get it to come on without success when the laptop is cold, but if I turn it on and wait 10 mins and let the laptop get warm the second attempt it comes on straight away. It seems my laptop only likes to work if it is warm.