Ok, so I have the iphone 4 on at&t and I want to jailbreak & unlock it for T-mobile. I downloaded greenpois0n version Rc6-1 & Rc6-2 and when I try to install it on the iphone 4 on dfu mode I keep getting a failed messages with a sad face. I must have done it over 50x already and nothing I do works. I read on a site to have itunes running on the background and not even that works. I am frustrated already... Can anyone help? I have the iphone for v. 4.2.1 on firmware 03.10.01. Please help!!