Hi, I have a pre-owned jailbroken iPhone 3GS with iPad 6.15.00 baseband running on iOS 4.3.1. I want to downgrade it to iOS 4.2.1 in order to fix some of my native iOS apps as well as to have better battery life. As suggested, I have saved iOS 4.2.1 and iOS 4.3.1 SHSH blobs using the latest version of TinyUmbrella. Anyway, where can I download custom iOS 4.2.1 IPSW for my iPhone 3GS? Thanks.
Asked by: Armand from Wichita, Kansas
If you are using a Windows, then you can follow this tutorial on how to jailbreak and create custom iOS 4.2.1 firmware using Sn0wbreeze 2.4 beta 1. You can get the stock iOS 4.2.1 from this link. On the other hand, Mac OS X users can refer on this blog post on how to use PwnageTool 4.2 to create custom firmware. Once you have successfully created the pre-jailbroken and custom iOS 4.2.1 for your device, you can now restore it into your device using TinyUmbrella. The steps on how to downgrade via TinyUmbrella can be found here. Also, you should use iREB when restoring the custom firmware in order to bypass all 16xx errors, use this guide if you don’t know how to use iREB. Lastly, you can unlock your iPhone using Ultrasn0w 1.2.3.