i think seasonpass is over for tethered 5.2.1 custom ipsw in a new computer .

i believe if you are already jailbrok apple tv and have already the files instaled  you can perform tethered boot

but if you have a  jailbroken apple tv and you take it to a new computer and wanna download the custom ipsw 5.2.1 it will not happen .  plz correct me im wrong