XBox 360 Power Supply Has RED LED On

I found this was caused, in my case, by a short circuit in the cord to my controller. I proved this by unplugging both wired controller from my XBox 360. The power supply then went from AMBER to GREEN when I pressed the ON button on the XBox 360. I put a new USB pigtail on my controller by soldering 3 wires and a shield ground to the pins where the original controller cable had been attached.