Here we are presenting step-by-step guide to untethered jailbreak iOS 4.2.1 on Apple TV 2G with GreenPois0n RC6. For this jailbreak to work, you need updated Apple TV2 to iOS 4.2.1.
How to Untethered Jailbreak Apple TV 2G iOS 4.2.1
1. First of all make sure that Apple TV 2 to iOS 4.2.1 is updated via iTunes. Check for updates through the software update in Apple menu.
2. Start GreenPois0n RC6.
3. When it prompts you for Apple TV 2G jailbreak, click Yes.
4. Follow all the ongoing screen instructions.
5. Leave the power disconnected and connect AppleTV2 using a micro-USB cable. Hold both the MENU and PLAY/PAUSE buttons for 7 seconds, till your Apple TV 2G is in DFU mode.
6. Once your Apple TV 2G is in DFU mode, click on Jailbreak button on GreenPosi0n RC6.
7. Wait till full jailbreak process completes.
Finally, you have your Apple TV 2G jailbroken on iOS 4.2.1