I had been wanting to jailbreak my iPhone 4 for quite awhile but since I had upgraded to Apple iOS release 4.2.1 there was not an untethered jailbreak available at the time and since I typically turn my iPhone completely off I didn’t want to deal with the untethered jailbreak. So needless to say when GreenPois0n rc5 was released I was pretty excited. GreenPois0n rc5 made it extremely easy to jailbreak iPhone’s running iOS 4.2.1. After running it for around a month now though I noticed that I really don’t install enough applications outside of what is available via the iTunes App Store to warrant the jailbreak and especially because I have personally noticed that with my iPhone jailbroken it had slowed down a bit. Not only had it slowed down but my battery appeared to be draining much quicker which I assume was from more processes running. I made the decision a couple days ago to roll back to the stock iPhone 4.2.1 firmware to see if my phone started running more efficiently. Below are instructions for rolling back the GreenPois0n firmware on an iPhone 4 to the Apple iOS 4.2.1 firmware release.
Uninstall GreenPois0n On iPhone 4 By Restoring Apple iOS 4.2.1:
I assume the below will work with other iPhone versions that were jailbroken with GreenPois0n however it has only been tested by me personally on an iPhone 4 that was initially on iOS firmware version 4.2.1. The below steps were completed on a Windows 7 Ultimate 64-bit laptop with iTunes version 10.2.0.34 however the concept should be the same with any OS with iTunes available.
- Download iPhone 4 iOS 4.2.1: Click here to download the iOS 4.2.1 IPSW file for the iPhone 4 from Apple. Again the instructions below have only been tested on the iPhone 4 however it should work on the iPhone 3GS as well so the iOS 4.2.1 IPSW can be downloaded for the 3GS by clicking here.
- Transfer Purchases & Backup iPhone: First connect your iPhone to your computer via USB and sync with iTunes. Once the synchronization is completed right click on the iPhone in the left navigation menu of iTunes and select Transfer Purchases from the pop up menu shown in the below example.
Once the purchases from your iPhone have been transfered to the computer right click on the iPhone in the iTunes left navigation menu again but this time select Backup from the pop open menu. Depending on the amount of data on your iPhone the backup will only take a short amount of time and once it completes continue on to step three below.
- Restore iOS 4.2.1 IPSW To iPhone 4: Once you have transferred purchases from your iPhone and backed up your iPhone to your computer you can proceed with restoring the 4.2.1 software. Please be aware that this will completely erase your iPhone and restore it to its stock settings however once you restore the backup we created in step two all of your settings, music, video files, etc. will be restored to the iPhone. Any applications you installed via Cydia, Installous, or any other third party applications while the phone was jailbroken will be lost though since they are not signed iTunes or signed by Apple. Your iPhone should still be connected to the computer via a USB cable. Highlight your iPhone in the left navigation menu to show the below screen within iTunes that will allow us to restore the 4.2.1 IPSW file to your iPhone which will overwrite or uninstall GreenPois0n.
Hold the Shift key on your keyboard while you click the Restore button located underneath the Version section of iTunes as shown in the above example image. This will open a Windows Explorer search window so you can navigate to the iPhone 4 iOS 4.2.1 IPSW file downloaded in step one as shown in the below image.
Select the file which will open the below iTunes warning pop up letting you know that your iPhone will be erased and then restored to iOS 4.2.1.
Click the Restore button in the pop up warning window to continue with installing iPhone iOS 4.2.1 back onto your iPhone. The restore process will begin immediately by extracting the iOS software as shown in the below example image.
You can watch the top status window in iTunes to follow the process which will include extracting the iOS 4.2.1 IPSW file, verifying the contents of the iOS 4.2.1 IPSW file, and restoring iOS 4.2.1 to your iPhone among other steps as well. It will take awhile to complete the process so just be patient. One your iPhone you can see a status bar letting you know the progress of the iOS 4.2.1 restore as well. Once the process has completed the below window will pop open in iTunes letting you know that the iOS restore process was successful.
Leave your iPhone connected to the computer via the USB cable while it reboots as there are more steps to complete to make sure you don’t lose any data.
- Restore iPhone Backup: Once the iPhone restarts you will see new drivers installed for the iPhone and then you will see the below Setup iPhone window in iTunes asking if you want to configure a new iPhone or restore the most recent backup to the iPhone.
Select the most recent backup of your iPhone created in step two and then click the Continue button. Depending on how much data you have on the iPhone this process could take quite awhile. In my case the entire process took about 25 minutes but there will be a status pop up similar to the below letting you know where you are in the restore backup process.
Once the process has completed the below window will appear above iTunes to let you know the iPhone restore from backup process was successful.
Once your iPhone restarts again it is likely you will receive a pop up warning letting you know some of the applications could not be restored to the iPhone. Likely these applications could not be restored because of iTunes error 0xE8008001 which means the applications are unsigned and cannot be installed on the iPhone unless it is jailbroken with AppSync installed. Anyhow proceed to the next step for more information on the warning and how to remove the applications so you don’t receive this message on a regular basis.
- Remove Unsigned Applications From iTunes: Backup the application files if you plan on jailbreaking your iPhone again however if you intend to keep the Apple iOS firmware on the iPhone from here on out then you don’t need to backup the applications. The pop up warning letting you know that some iPhone Apps could not be restored will look like the below example image.
If you click the + symbol next to “5 total warning” (the number will depend on the number of unsigned apps) something similar to the below window will display letting you know the error code for each application that could not sync. In this case is because of unsigned Apps so error code 0xE8008001 will display next to each App.
Click OK to close the pop up window and follow the directions below to remove the unsigned apps from iTunes. Click Apps underneath Library in the iTunes left navigation menu as shown in the below example image. Once the list of Apps is displaying click Genres at the top of the list of iTunes Apps also shown in the below example image.
The last App Genre listed should display as Uknown Genre since these apps are not signed they are not assigned to a Genre and instead of deleting each App individually you can delete the entire Genre to save time. I would suggest first clicking on the Unknown Genre so you know exactly what Apps are being deleted from iTunes. Once you have verified all of the Apps are unsigned and you have backed them up if necessary right click on the Uknown Genre and select Delete from the pop up menu as shown in the below example image.
Once you select Delete from the pop up menu the below warning will display verifying you want to remove the selected Apps from your iTunes Library.
Click the Remove button to proceed with deleting the unsigned Apps from your iTunes Library. One more pop up will appear asking if you want to move the Apps to the Recycle Bin or if you want to simply unlink them from your iTunes Library. I personally moved the unsigned Apps to the Windows Recycle Bin but it doesn’t matter either way.
Click either Move To Recycle Bin or Keep Files to remove the unsigned Apps from your iTunes Library.
Your iPhone has now been restored to the Apple iOS 4.2.1 firmware and in my case my iPhone is again running much better. My iPhone’s battery life is also lasting much longer. There is definitely a lot of upside to jailbreaking your iPhone with GreenPois0n but in my case it wasn’t worth the performance and battery life hit.