Recently I downloaded the iPhone beta 3.0 firmware upgrade and decided (without thinking it through) to update my phone to use the new version. In hindsight, Apple makes it pretty clear this is a bad idea, and warns you that you won’t be able to revert to a prior version of the software:
But warnings were meant to be ignored, so I blithely went ahead and updated with the new firmware. Immediately after doing so, I had a d’oh moment when I realized I better not have my business phone running on beta software, so I wanted to revert.
Well, this turned out not to be so easy, as soon as I tried to reload the prior version of software, I got to a place where the firmware restore would simply stall, and eventually fail.
I tried every version of firmware on my machine, including the beta, and my phone simply couldn’t be reloaded.
Just when I thought I was going to have to give up and take the phone to the Apple store, I remembered that jail breaking your phone involves a process of putting your phone into DFU mode (allegedly stands for Device Firmware Update, but I think it stands for Dumb Frantic User). In essence this does a hard reset of the phone and puts it back to a factory clean state.
Once I fired up PwnageTool, and ran through the process of jail breaking my phone (mostly because it has a step that helps you through the steps of getting your phone into DFU mode), the restore of the firmware worked again, and I was able to restore to the current 2.2.1 version of the firmware without any problems.