Instructions
Turn off your Xbox 360 console.
Unplug the power cord from the back of the console. Disconnect the power supply unit and remove the plug from the wall outlet.
Reconnect the power cord to the power supply unit, making sure it is firmly in place. This connection can easily be pulled out of place and is a common cause of Xbox 360 power problems.
Reconnect the power cord to the Xbox 360 console and plug back into the wall socket.
Turn on your Xbox 360 console. If the red light occurs again, repeat the process. If your console still doesn't work, you need to request a repair from Microsoft's online support site.