[Jeckel]

The screen should be black during the entire restoring process. It could be that it isn't staying in DFU mode (it's trying to go into recovery, which as you've seen wont work). You can adjust the time you hold the power and home buttons for slightly less than 10 seconds (start at that point, exactly, then keep reducing the time to 9 seconds, 8 seconds, 7 seconds, 8.5 seconds. Just try a bunch of different times), but release the home button at the moment you hear the 'beep' that confirms the computer has detected a USB device.