Hopefully this helps someone who may get this error…
I ran the new version of seasonpass on my jailbroken 4.3 Atv and everything went smoothly. It went into DFU mode ok, iTunes started and it went though the various stages of verifying the firmware with Apple and installing it. After a while iTunes gave a 1602 error during verification of what had been installed.
Rather than running the whole process again I booted up the Atv and saw the red FC logo with version 4.4.4 of ios installed. I then installed the Atv Flash software, Xbmc etc without any problems whatsoever.
It is running flawlessly and I am very happy, thanks Firecore for an amazing product.