ATV 2 Just purchased on 6.0.2 software - Need to downgrade

i have just purchase an apple tv 2 and it has come with the 6.0.2 software, i have never had one before so i have no shsh blob files etc.

 

i need to downgrade software to a software which i can use a jailbreak unthethered.

 

ANY IDEAS WHAT TO DO I HAVE NO IDEA.