surface RT

hey all I have a little problem, I was given a surface rt it was updated about 2 weks ago to 8.1 so I presume it was installed with 8.0, ive put the 8.0 image to a flashdrive but when I go through everything it still resets to 8.1 also when I try to get to the bios to turn off secure boot by holding vol up+power then let go of power nothing happens but black screen then I have trouble turning the device back on. after about 3 mins I am able to turn the device back on. can someone please help me im at a loss and want to desperately go back to 8.0 so I can jailbreak to open the device up more. if someone can help me please mail me leeshawslater773@gmail.com as I don't log in often.
many thanks
GM