Video Settings Won't Reset

This is an original Xbox 360.

Hey there KDB! I just tried this on my console and it worked the first time. As soon as you turn the console on (via the guide button on a wireless controller), press and hold (Y) and Right Trigger. Hold these through the logo screen and into the dashboard. Do not let go of these buttons until the console resets or you see the dashboard fully loaded (Home Hub). Let me know if this helps, thanks!

Thanks for the response.  I tried this with the controller wired and wireless.  As mentioned I tried many times.  I held the buttons down for over 5 mins, but no image ever appeared on the TV.  Do I need to hold it for longer?  Does it make a difference which video connection type I use when doing the reset procedure?  Thanks again.

I would say use the simplest AV connection you have, like the included composite (three prong) cable that came with the console. You could also try hooking up to a different TV to see if that yields different results.

When you say no image ever appears, you mean you never see the Xbox logo or anything? What do you see, just black screens? Let me know, thanks!

the only thing that will display on a TV (full HD capable) is an image occupying the right half of the screen while using an HDMI cable.  The image is completely scrambled so unable to see anything understandable.

I connected the xbox 360 into a Sony HD TV, and instead of the scrambled image, the TV just reported that the 1920x563 was an unsupported signal.  Is there some device I can hook this up to that will display the image just until I can work my way through the menus to reset the video?

I'm a little confused now, you first mentioned that when trying to do the video settings reset that you saw no image at all, and now you say that there is still a distorted image. You shouldn't have to work through any menus if you reset the video settings. Are you certain you are doing this in the proper order (support.xbox.com/.../image-on-your-tv-is-unclear)? Please let me know, thanks!

Please see the last sentence of my original post for clarification.  I did follow the reset procedure exactly as written.

"Someone" messed with my XBOX 360 video setting so that now the only thing that will display on a TV (full HD capaable) is an image occupying the right half of the screen while using an HDMI cable.  The image is completely scrambled so unable to see the menus.  Tried the procedure to power up the console from the remote, then hold down the Y + RT buttons.  According to the support note this should resent the console video and the XBOX should reboot.  I've tried this a dozen times but no display and no reboot.  For the record I have also tried composite and component video connections, and the TV will then report that there is no signal.

Once the xbox starts up, it is responsive to the controller.  You can barely make out that the image on the TV is changing as I press the D-Pad.  The box has the old menu system, as it was not upgraded yet.  If I knew the correct sequence of up, down, right, A button entries to get the video reset I could do it that way.  

Is it possible that the video out was set for 50 Hz and that is what is causing the problem (I'm in the US).

Starting to think this is a hardware problem.  I understand from a repair shop that there is a chip that is responsible for adjusting the image to fit the screen that sometimes goes bad.  Taking it for diagnostics this week.