Did some more digging, and this is what finally worked.
When you connect an xBox 360 to a TV with HDMI for the first time, the xBox 360 often defaults to the highest resolution it can produce. For many TV’s this may be too high. You may receive a message like “UnSupported” or “Not Supported” or “UnSupport”, etc.
So you cannot see the xBox 360 menus, but you will probably hear the boot up sounds, and menu ticks/clicks. If you ask people that aren’t intimately familiar with this specific problem, they’ll tell you to check the HDMI cable, the 360, etc. Don’t listen to
them.
The solution to this problem is to blindly navigate into the Display settings to change the display resolution to something that your TV can display.
Here’s a step by step guide:
1. Connect your 360 to your TV with the included composite (Yellow, Red, White) cable .
2. Ensure you’re running the new Xbox dashboard (Avatars support).
3. Ensure no profile auto-sign’s in at boot up.
4. Power off 360 and TV. Connect the HDMI cable between them.
5. Hold down the controller’s xBox button for 3 seconds to power on, and wait for about 20 seconds.
6. Press right on the (dpad) left analog stick 9 times, to navigate to the System Settings menu.
7. Press the A button 4 times. (This will go to System Settings, Console Settings, Display, HDTV settings.)
8. Press up twice on the (dpad) left analog stick. Press A.
9. If no picture appears, wait 15 seconds, Press up again and press A. What you are doing is selecting lower display resolutions. Once you have a picture, you can try other higher resolutions, if you want, and it will revert back if you don’t confirm it
is ok. The 360 will remember the setting you finalize.
Troubleshooting: Power off both 360 and TV. Switch back to the composite cable. Try steps 1-7 again to verify it is navigating correctly. If your profile is auto-logging in, the 360 will start on the “Welcome” tab, rather than the “Play Disc” tab, in which
case, you would have to press up once, before the 9 rights, to get to the System Menu. (The end.)
