I bought a h2h from official supplier advertised on here. I am also having the same problem trying to flash. No matter what I do it just won't go into flash mode. Tried 4 different USB sticks, format with hddguru, then Windows to fat32. Nothing. Was told about the sandisk-cruzer-blade 8gb. Went to asda bought one, tried again. Nope.
I just don't think it working right. Maybe a faulty batch.
I trying dsayers image btw, unzipped and only zgemma folder on to a stick.
Ended up just doing bare bones setup on openatv 5.3. I got it working now ok with test dual lines.