what does half a red ring round the power button on my xbox 360 mean? Answered

if you are trying to fix red light of death on your own i recommend you to visit this blog at xbox ring of death fix in under 40 minutes

DUN Dun dun!

http://en.wikipedia.org/wiki/Xbox_360_technical_problems

And perhaps

https://www.instructables.com/id/Fix-the-Red-Ring-of-Deathwithout-towels/

This is a common problem caused by Xboxes being craply-built/designed.
There are a lot of fixes on this site, under the title "Red Ring of Death". Half of one should feature somewhere, but this is what the official line is (overheat):
http://support.xbox.com/support/en/us/nxe/kb.aspx?ID=907533&lcid=1033&category=hardware

L

1. Let the Xbox 360 console cool.
   Note You may have to wait several hours for the console to cool enough. Do not turn on the console when the console is hot.
2. Verify that the console has sufficient ventilation and that the fan is operating. For more information about ventilation, see the "More Information" section.

• Do not block any ventilation openings on the Xbox 360 console.
• Do not put the Xbox 360 console on a bed, on a sofa, or on any other soft surface that may block ventilation openings.
• Do not put the Xbox 360 console in a confined space, such as a bookcase, a rack, or a stereo cabinet, unless the space is well-ventilated.
• Do not put the Xbox 360 console near any heat source, such as a radiator, a heat register, a stove, or an amplifier.

Your Xbox is half-dead

2 of the lights behind the power button are out?