I've been trying to jb for the past hour but my iPhone 4 just turns on after rensnow says exploting waiting to reboot I'm sore I'm following the steps right.
you could try using greenpois0n if thats easier but if you did it correctly then it will work so there must be something your missing out or not doing right,
did you go through the cydia settings and make sure you have the relevant boxes ticked and correctly put your device in dfu mode while its off...etc?