When I returned from holiday I discovered my Xbox 360 would not turn on and displayed three red segments around the power button. I have reviewed the forums and followed all the following troubleshooting steps:
The light on my power supply unit is red.
Check your power supply cables
Turn off your console. Unplug the power supply from your console, and remove the power cord from the outlet and the other end of the power supply. Reattach the cables, making sure everything is plugged in nice and snug. Also, be sure you’re plugging directly into the wall, and not into a surge protector. Turn your console back on. If the light on the power supply is still red, continue to the next step.
Try a different outlet
Turn off your console. Unplug your power supply from the console and the wall outlet, and then take the power supply and console into another room. Don’t worry about the video cables for now.
Plug the power supply into an outlet in the room, and then plug the power supply into the cable. Make sure everything is nice and snug, and then power on the console. (The console will flash four red lights, but only because the video cable isn’t attached, so don’t worry.)
What color is the light on the power supply now? Is it green? If so, then the issue is with wall outlet, and not the power supply or console (be sure not to plug into that outlet until the outlet has been repaired, or until the power strip on the outlet has been replaced).
Let your power supply cool down
Turn off your Xbox 360 console. Unplug the power supply from its outlet and from the console, and let the supply cool down for one hour. Once cooled, reattach the cable to the console and outlet, make sure everything is nice and snug, and turn the console back on. If the light on the power supply is still red, the power supply will need to be replaced.
However, the Power Supply light is still red so I need a replacement but can not seem to find a supplier anywhere in the United Kingdom.