I was able to jailbreak my apple tv 2 successfully using Seas0nPass. I downloaded aTV Flash and it transferred the files. Since the new jailbreak for iOS5.1 is tethered, it lost the jailbreak when aTV Flash restarted it.
How do i get aTV Flash to work if it restarts the apple tv 2 which in turn loses the tethered jailbreak?
What makes you think the jailbreak has gone? Installing ATV Flash removes the Firecore logo if that is the change you are seeing. However you should now have the FireCore maintenance app installed for installing and managing the FireCore apps.