I have just purchased my first Apple TV unit today. I also bought an 8Gb San Disk Cruzer memory stick, erased it to zero. I bought the aTV Flash download and followed the instructions to the letter.
My problem is that I cannot get my Apple TV to boot from the memory stick. If I let the Apple TV boot as normal without the stick inserted, then plug it in once booted then the stick is recognised and the little orange activity light on the stick lights up.
However, if I unplug the Apple TV, remove the stick, wait for a few seconds and insert the stick and plug the stick back in prior to powering up then I get 1 faint flicker, the Apple TV starts to boot, a slightly longer flicker off roughly 2 or 3 seconds and the stick fails to be recognised. The Apple TV boots as normal and the stick light remains off. It’s the same as the previous poster - it’s initially recognised as being plugged in, but clearly not being picked up as a boot.
I’ve gone through your manual, plus the tech video on YouTube. Nothing is different.
At the moment I am using an old iBook G4 installed with OSX V10.4.11. My 20" iMac Intel Duo is in for a minor repair, but I don’t think this should have any baring on whether this works or not.