I have an iPhone 3G running iOS 4.1 with modem firmware (baseband) 05.13.04, it is jailbroken and unlocked and open to any UK network.
Anyway I wanted to sell this iPhone so I would like to restore the iPhone to delete all personal data, etc, so I believe I could create a custom firmware of iOS 4.1 for it with redsn0w and then restore in iTunes. But this doesn’t work as Redsn0w will not create a custom ipsw for 4.1.
If you want to use jailbreak tools such as redsn0w, you’ll need to know which version did you use so you know if that redsn0w version is compatible with custom iOS version you want to create.
The other useful jailbreak tool to create custom firmware is sn0wbreeze.
You could just create a custom firmware for iOS 4.2.1 with sn0wbreeze. Just update it to the latest firmware version for iPhone 3G, so the buyer doesn’t “accidentally upgrade” in iTunes when plugging in the iPhone to the computer and broken the phone.
The latest versions of sn0wbreeze supports all the way back iOS versions starting from iOS 3.1.3 and so on (including iOS 4.2.1 and iOS 4.1).
Click to Download sn0wbreeze (download the latest version which iOS 4.2.1 is already supported).
Click to see: sn0wbreeze for iOS 4.2.1 (Guide)
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