I know title of post sounds very exciting to those who just got their hands on iPhone 4 and it comes with iOS 4.0.2 out of box. iOS 4.0.2 out of box means no jailbreak possibility with jailbreakme, since you haven’t saved 4.0.1 SHSH on file or with Cydia you can’t downgrade to 4.0.1 Here comes a new twist, an user named CodeBlue has discovered an unconfirmed method that may allow you to downgrade your 4.0.2 iPhone to 4.0.1, jailbreak, patch the safari exploit with Saurik’s patch and be jailbroken safely.
Note : I did not try these steps. They sound good to me in theory and others are reporting some success. After all, you have nothing to lose if you are already stuck on 4.0.2 without an SHSH in Cydia. Here are the steps:
If you were lucky to save your Cydia SHSH for 4.0.1, you can always downgrade iOS 4.0.2 to 4.0.1 for iPhone 4, iPhone 3GS
Update : According to recent comments most of the attempts are failed, unfortunately i am still looking for a new 4.0.2 device in my local friends. I’ll post my experience here sooner or later once i get a new iDevice with iOS 4.0.2 out of box.
1. Download firmware 4.0.1 for your iPhone.
2. Rename the file you just downloaded. ipsw to. zip and extract it with any achieve program for Windows or Mac
3. Look for *buildmanifest.plist* and open this file with notepad or text editor and replace all entries "8a306" with "8A400" and save the file, now repeat the same procedure with the file *restore.plist*
4. Download firmware 4.0.2 for your iPhone, rename it to. zip and unzip it with any achieve program for Windows or Mac.
5. Take all the files from the 4.0.1 and drag them over to the 4.0.2 zip archive that you have open.
6. Delete all the dmg files that have 002 at the end, leaving only the 001 files left.
7. Save the file and rename it to ipsw. This will be the file that used to downgrade.
8. It is not necessary for this procedure, but it will help you edit your HOSTS file in order to have a redirect server to Saurik when iTunes will check if your device is compatible with the firmware version you want to install. Here’s how:
MAC : Using Finder, click on "Go to Folder" menu "Go" and type / etc /. Copy the file "hosts" file on your desktop then open it with Text Edit and at the end of the file add the string:
Always save the file on your desktop and then drag it back into the folder "/ etc"
WINDOWS : Go to Start, All Programs, Accessories and click Notepad with the right button, select "Open as Administrator". Now go to C: / Windows / system32 / drivers / etc and open the hosts file, adding the end of this line:
Save the file.
8. Now put the iPhone in DFU mode and restore with the file you just created Step 7.
Note: this only works due to the similarities in 4.0.2 to 4.0.1 and 4.0. This will not be a way to downgrade to 3.1.x and may not work in future firmware updates.