Can you get it to boot at all.... I had to use Safe Mode on one of my windows 8.1 boxes, Windows 8.1 DOES support the F-8 feature but... per Windows. It boots so fast (Fast and Windoze in the same sentence????) your odds of hitting F-8 at the right instant approach zero.
In my case it booted, and I entered but there was something I needed safe mode to do (And did).
MS-CONFIG Start run msconfig ok
On the BOOT tab I ticked "Safe mode"
And when I finished my job.. Re-entered MS Config and unticked it.
All good now.
But that's 8.1.. Do not know if you can do that in eXtra Painful.
I'm told Windows 10 will be an improvement,, Have yet to get it to a point where I can load it into one of my older compters and test it. (Still in ISO format).