I used redsnow to jailbreak iphone 3g with 4.2.1 and everything went fine until the end when the phone tried to reboot its stuck on the apple logo. I tried to DFU again and doesnt work. iTunes on my computer isnt for this iphone. What can I do???
This happened to me the first time I used jailbreak.com on my old 3GS. Although this video displays the iPhone 4, the steps will also work on your iPhone 3G as well. You will need to turn your iPhone off before getting it into DFU mode (the steps are in link).