If you either have a new iPhone 4 with iOS 4.0.2 pre-installed by default or upgraded to the new firmware without saving your SHSH blobs first, here's a trick that might allow you to downgrade to iOS 4.0.1 thus allowing you to jailbreak your iPhone via the JailbreakMe website. In a nutshell, you just have to slightly modify the official iOS 4.0.1 ipsw file, and then transfer all the contents to the iOS 4.0.2 ipsw file. This will allow you to fool your iPhone 4 and iTunes into believing that it's installing iOS 4.0.2 while the truth is its iOS 4.0.1. This can’t jailbreak iOS 4.0.2 and iOS 3.2.2 since this new iPhone/iPad firmware plugs the exploit used by this particular iPhone jailbreak. Read more in our articles including "Downgrade iPhone 4 from iOS 4.0.2 to 4.0.1 sans SHSH blobs to Jailbreak" and "Apple announces iOS 5 at WWDC 2011".
If you either have a new iPhone 4 with iOS 4.0.2 pre-installed by default or upgraded to the new firmware without saving your SHSH blobs first, here's a trick that might allow you to downgrade to iOS 4.0.1 thus allowing you to jailbreak your iPhone via the JailbreakMe website. In a nutshell, you just have to slightly modify the official iOS 4.0.1 ipsw file, and then transfer all the contents to the iOS 4.0.2 ipsw file.
This will allow you to fool your iPhone 4 and iTunes into believing that it's installing iOS 4.0.2 while the truth is its iOS 4.0.1. This can’t jailbreak iOS 4.0.2 and iOS 3.2.2 since this new iPhone/iPad firmware plugs the exploit used by this particular iPhone jailbreak.
Our coverage of downgrade ios 4.0.2 includes: "Downgrade iPhone 4 from iOS 4.0.2 to 4.0.1 sans SHSH blobs to Jailbreak"; "Apple announces iOS 5 at WWDC 2011"; "iPhone 4 jailbreak (JailbreakMe) website Alternatives". Each article provides unique insights and information.