Hi
If worse comes to worse and you are are unable to get it to boot, and need to do a restore from the recovery partition...
You should create a Ubuntu disk and boot your computer with it.
This will allow you to copy all of your data off of the computer before you do the reset.
Take your time and make sure you get everything, email addresses favorites etc.
It's always dangerous to shut your computer off during the shut down process.
Especially if it's doing updates.
Hope it doesn't go that far, but Windows 8 isn't quite as easy to recover as Windows 7 which would let you do a repair install that retained all your data and software.
http://www.ubuntu.com/download
If you get to this point and need help, just ask here.
Good...