I am running firmware 3.1.2 with baseband 05.11.07 on my jailbroken and unlocked iPhone 3G I am trying to figure out how to upgrade the firmware to 4.2.1 without bricking it. I downloaded the 4.2.1 IPSW file and I have Redsn0w _0.9.6rc12, but I can't figure out how to install the 4.2.1 firmware from the IPSW file. I thought the way to do it is to go into iTunes and have iTunes do it using the 4.2.1 IPSW file by clicking on Restore. But when I do that iTunes says it will download and install the latest version of the Firmware. So I did not proceed thinking I would not have the option at this point to direct iTunes towards the IPSW file saved on my computer. Am I doing something wrong here? Cheers.