Tried several times (dozens) to get tethered boot to work according to the latest SeasOnPass Version 0.6.7 (23).
Unit would never enter DFU mode according to the instructions (disconnect briefly than add mico usb first, then Power, than Menu/Play etc).
The only way to enter DFU is with micro-usb only, but adding Power later stops the process from completing.
Finally, the ATV2 just died - no lights. Nothing I can do to bring it back (1 day old).
It seems to me that the steps are incorrect. We need a better explanation of how to get the unit to entered DFU for tethered boot. Other uses have suggested doing the reboot step first, but didn't help in my case.