I just had a similar problem with a Duox2 on a v1.6 xbox. When connected using the HDTV kit (MSFT product one), the MSFT dash came up ok. When I tried booting into the flashbios, I would get a blank screen.
If I switched to the stock composite (3 rca, yellow-red-white) cable on the xbox, then I had signal, no problems.
Very odd. The Duox2 on a 1.0 xbox did not have the same issues.
Furthermore, flashing on this v1.6 xbox went horribly wrong. I flashed bank0 but it did not work (flashing red). I then tried booting on bank1, but could not get that to work. I ended up having to unplug the DVD, then the system booted. I then flipped the switch to bank0 and tried flashing it (using the network flash). Same results. This went on for a couple of hours, during which I tried different BIOSes (including an attempt to put the flashbios back on). All attempts failed.
Out of desperation I tried flashing bank1 with M8 and that yielded the same results.
I now have a v1.6 xbox with a Duox2 that has both banks with "bad flashes". Sucks.
