Untethered 4.2.1 Jailbreak iPhone or iOS 4.2.1 devices using Greenpois0n RC 6.1 – step by step guide

Finally highly reputed Chronic Dev Team released the Greenpois0n RC 6.1 which comes with iBooks fix. Before that Chronic Dev Team already added Apple TV 2 support and fixed emulator compatibility in RC 6 and Verizon iPhone 4 support in RC 5.4.

Supported Devices

Following is the list of devices supported by Greenpois0n RC 6.1.

• iPod Touch 2G (all bootroms)
• iPod Touch 3G
• iPod Touch 4G
• iPad 1G
• iPhone 3Gs (all bootroms)
• iPhone 4
• iPhone 4 Verizon
• Apple TV 2

Read this before jailbreaking you iOS 4.2.1.

Please make sure that your iOS device is running iOS 4.2.1. To do that you need to go to Settings -> General -> About. In case if your iOS device is running older version please upgrade it to iOS 4.2.1 using iTunes. You also need to reinstall iOS 4.2.1 using iTunes if your iPhone or iOS device has been jailbroken with running Dev Team jailbreak Monte. If you need to download iOS 4.2 you can download it clicking on the device name.

iPhone 3G

iPhone 3GS

iPhone 4

iPod touch 2G

iPod touch 3G

iPod touch 4G

iPad 3G & Wifi

Requirements:

• iOS device running 4.2.1.
• USB cable to connect your iOS device to computer running windows.
• Greenpois0n RC 6.1 for windows
• Greenpois0n RC 6.1 for Mac

Now follow the following instructions.

Step 1: Download Greenpois0n RC 6.1 and extract the content of Greenpois0n RC 6.1 zip file in folder.

Step 2: Execute Greenpois0n.exe located in folder you just created in step 1.

Step 3: Using USB cable connect your iPhone or iOS device to your computer.

Step 4: If you are using Greenpois0n to jailbreak Apple TV 2 click on “yes” but if you jailbreaking iPhone click on “No”.

Step 5: Click on “prepare to jailbreak (DFU)” button.

Step 6: You will be able see the following screen. Follow the instructions as displayed on the screen to launch DFU mode.  Once you have successfully entered DFU mode your iOS device screen will turn black.

If you are unable to enter into DFU mode restart device and try again.

Step 7: Once you are in DFU mode click on “jailbreak” button which is located on the left lower side of the greenpois0n window.

Step 8: If you have done everything correctly so far you should be able to see a white screen on your iOS device screen after which your device will display some codes running. Device will restart and you should be able to see Greenpois0n icon and Greenpois0n program window on your computer will look like this.

Step 9: Once device loads jailbroken firmware, locate loader application on the home page. Launch loader application to install Cydia on your iOS device. Once you have installed Cydia you will be able to see Cydia icon on the home screen.

Congratulations, now you have untethered iOS 4.2.1 jailbreak.