ipod touch help! urgent!!?

i jailbroke my ipod touch using ziphone, and it was fine, so my brother asked me to do his. i tried, and it stopped in the middle with a black screen and white words that says "if you wish to boot the system: exit" along with a bunch of other stuff. if i turn it off and on it ends back on this screen. if i plug it into the computer it doesnt even recognize it. it just goes to the same screen. help! please!