Jailbreak iPhone 4G & 3GS – Untethered
Step 1: Create a Backup
NOTE: If your iPhone 4 relies on an unlock, do not update to the latest version yet as doing so will upgrade your Modem Firmware (Baseband), making it impossible for now to unlock. Do not use this guide if you also want to unlock.
Before jailbreaking your iPhone, you need to have a backup of your device using iTunes. To do that, simply follow the steps as instructed below.
1. Connect your iPhone to your PC.
2. Launch iTunes.
3. On the left pane of iTunes interface, you will see list of devices connected. Look for your iPhone.
4. Click on your iPhone, right-click, and select Back Up.
Step 2: Upgrade iPhone Software
Download the iOS 4.2.1 software by Right clicking and “Save Target As..” or “Save Link As…”, do not open the file. Wait until this file finishes downloading (5 – 15 minutes).
Upgrade your iPhone firmware to iOS 4.2.1 using iTunes. Connect your iPhone to the PC and select your device on the left pane of the iTunes interface. In the Summary tab, hold Shift-key on your keyboard and click Update. And then locate your downloaded iOS 4.2.1 file to start the software upgrade. (Don’t worry; iTunes will do all the rest of processes here.)
Step 3: Download the Jailbreak Software
Download the Jailbreak software by Right clicking and “Save Target As..” or “Save Link As…”, do not open the file. Wait until this file finishes downloading (1 -5 minutes).
Step 4: Connect and Launch Software
Connect your iPhone via USB cable to your computer and launch the jailbreak software. Click on the file greenpois0n.exe you just downloaded (If on a Mac, you will need to unzip / extract all the files first). Launch Greenpois0n.
Step 5: Preparing Software
– Connect the iPhone to your PC and power it off
– Click ‘Prepare to Jailbreak DFU’ in the Greenpois0n interface.
Step 6: DFU Mode
Follow the instructions on the Greenpois0n interface to put your iPhone in DFU mode (this might take you a couple of tries to get it correct, don’t worry).
* Press and hold the sleep button for 2 seconds
* Press and hold Home button for 10 seconds, while continuing to hold Sleep button.
* Release sleep button; continue holding home for 15 seconds.
If you failed to follow the instructions correctly, don’t worry. It won’t mess your iPhone. You will be asked to try it over and over again until you successfully put your device in DFU mode.
Step 7: Jailbreak Software
Step 7: After successfully entering DFU mode press the jailbreak button. The jailbreak software will now start “Jailbreaking” your iOS device untethered on 4.2.1.
Step 8: Jailbreak Installed
Your iPhone should now be successfully jailbroken on iOS 4.2.1.
Step 9: Loader
Step 9: Now launch Loader app from your homescreen.
Step 10: Cydia
After launching the loader app, click on Install Cydia.
Step 11: Restart
Restart your iPhone then run Cydia. Let it do all the required updates.
This is it! You are done !