We just reported about Greenpois0n RC6 release to untethered jailbreak Apple TV 2G on iOS 4.2.1, if you have recently bought Apple TV 2G and not sure how to jailbreak greenpois0n then here is complete step by step guide to jailbreak Apple TV 2G on iOS 4.2.1.
Stuff Needed
2. Download iOS 4.2.6 for Apple TV 2G
3. MicroUSB cable to connect Apple TV 2 to Mac
How to Untethered Jailbreak Apple TV 2G iOS 4.2.1
1. Make sure you have updated Apple TV 2 to iOS 4.2.1 via iTunes, if not then check for updates through software update located in Apple menu.

2. Now Start Greenpois0n RC6 and click on Yes when it prompts for Apple TV 2G Jailbreak.
3. Follow onscreen instructions to put Apple TV 2G in DFU mode,
Connect your AppleTV using a micro-USB cable (leave power disconnected), and hold both the ‘MENU’ and ‘PLAY/PAUSE’ buttons for 7 seven seconds to put your Apple TV 2 in DFU mode.
4. Once your Apple TV 2G is in DFU mode click on Jailbreak Button on Greenpois0n RC6 and let it complete the rest of the jailbreak process.
That’s it, if you have followed above steps properly your Apple TV 2G will be jailbroken on iOS 4.2.1.








