How To: Untethered Jailbreak Apple TV 2 with RC6

• Another kudos to awesome effort of Chronic Dev Team!

• Finally the Jailbreak for Apple TV 2 has been release by the fantastic Chronic Dev Team! When the team release GreenPois0n RC5, it did not support Apple TV2. 
• Greenpois0n RC6 now available for both Windows & Mac machines that untethers Apple TV 2G jailbreak on iOS 4.2.1.

To be able to untether iOS 4.2.1 on Apple TV 2G, you have to follow the step by step guide posted here or here and you'll get Apple TV 2G untethered jailbroken on iOS 4.2.1. 

STEP 1: Your device must be on iOS 4.2.1, then download GreenPois0n RC6 for Mac OS X

STEP 2: Launch GreenPois0n RC6 then connect your ATV2 into your Mac via USB and click on Jailbreak as shown below:

 

STEP 3: Follow the instructions shown on the screen to enter DFU mode:

 

STEP 4: Once jailbroken, you'll get Cydia installed on your iOS device and you won't need to use Just tethered boot right now option anymore.

 

Download links of greenpois0n RC6 below:

Download Greenpois0n RC6 for Mac OS X
Download Greenpois0n RC6 for Windows
Download iOS 4.2.1 for Apple TV 2G

HOW TO: Untethered Jailbreak Using GreenPois0n RC5 for iOS 4.2.1

Greenpois0n 1.0 RC5 ***

Description of the software:

  greenpois0n will Jailbreak your iDevice.

Supported iDevices:

  - iPod Touch 2G (all bootroms)

  - iPod Touch 3G

  - iPod Touch 4G

  - iPad 1G

  - iPhone 3Gs (all bootroms)

  - iPhone 4

  - iPhone 4 Verizon (_not_tested_)

  - AppleTV 2

Requirements (check this !)

  - A supported device (see above)

  - The device should run iOS 4.2.1. Please check on the device in the Settings -> General -> About page.

    If your device is running an older version, please upgrade iOS first using iTunes.

    *** If you want to SIM Unlock, preserve your baseband using TinyUmbrella ¬®***

  - at least MacOSX 10.5

Notes (checks this also !)

  - If your device is jailbroken with iPhone Dev Team's Monte, please restore to fresh 4.2.1. first

  - If Cydia doesn't show up after Loader, you may need to reboot the device

  -This version of greenpois0n doesn't include a patched activation system. You'll need to activate your device using iTunes

  - WE DO NOT SUPPORT PIRACY !

Instructions

  1.     Plug the device to your computer using the USB cable

  2.     Quit iTunes if it shows up

  3.     Start greenpois0n.app

  4.     Follow instructions

  5.     The device will boot a 1st time with verbose text on screen. This operation will install the jailbreak on the device.

  6.     The device will reboot normally

  7.     Start the Loader application (green icon on the SpringBoard), and follow instructions to install Cydia

Source: Edoras FotoZine