I had the same problem. I was using older HDMI cable and as soon as I switched from 480p to 1080p I only received a black screen. I couldn’t figure out what was wrong or get to settings again. I switched to a Ethernet fast HDMI cable and all worked fine.
Turn both devices off.
Plug in TV HDMI. Then Xbox 360.
Turn on TV then Xbox 360.
Go to settings on ...