unlocking Iphone 3G

[_Hotsauce_]

Yes, I did post this in the mobile chat forum, but thought I'd post it here as well.

Got some issues with my 3G, just got a new one through Warrenty but it came preloaded with IOS 4, and I wanted to go back to 3.1.3, which I did with no problems. Obviously, I wanted to jailbreak and unlock it, like my old phone, went through the process, installed cyida etc, installed blacksn0w, went to restart and now it can't get past the Apple load screen.
The Apple comes up, and it gets the loading progress thing, there are some odd lines at the top of the screen, and it just sits there doing the twirly load shit, resets, repeats etc.
Not to sure what to do now?

[underscore]

reset it back to normal, and start again?

[The_Situation]

Plug the phone into your computer. Put it in DFU mode. ---> Hold the home and power button for 15 seconds (the screen should go blank) then release the power button and keep holding down the home button.
You should get something on your screen. You should be able to restore it on itunes now.