hello world.
I´m a Toshiba laptop with 1TB Harddrivespace, intel core i5 and amd radeon graphics (;
my problem: no matter what I do win8.1 stays

-I burned the Kali .iso via ISOtoUSB on an 8GB stick.
-Executed the comand prompt shutdown.exe /f /r /o /t 00
-Choosed the USB option in the boot menu

- after several minutes of a toshiba loading screen windows starts and udates

It`s my first time changing an OS so I`m a complete n00b when it comes to boot or OS problems. So please keep it simple... (if possible)

I'm thankful for every advice.