I'm using a samsung 9 series laptop with windows 8.1 and was trying to run the Gparted ISO from USB on it.
In order to change the boot settings I was trying to get into the BIOS, but for some reason I was not able to get in via F2, or any other key... What did work was to press F4 (some recovery tools) and from there it was possible to reboot going into the UEFI BIOS settings.
Once in the BIOS I changed the BIOS to CMS instead of UEFI and I also disabled the secure booting. Next to that I prioritized the USB drive in the boot sequence (I moved it to the top). Then I was able to het the Gparted ISO booting from my USB disk. However, now I want to start windows 8.1 again but somehow I'm only able to boot from USB! If there is no USB drive in the PC, then the power light goes off, then on again and I get the option F2 for BIOS and F4 for settings, but these keys are not working at all.... once past that, power light goes off again and the cycle starts again...
I tried with a windows 8 recovery USB stick. There are some tools available there, but not the one that I used to get into the UEFI settings as mentioned above.
So I'm stuck with the USB at booting and I don't know how to get into the BIOS to change the boot sequence again (assuming this is what I would need to do).