Xbox 360 code 0002

Question

i have replaced the x-clamp method, still had 3 rd's so been trying differant methods to sort it i've just tried unscrewing the heatsink untill it was loose then unplugged the fan and turned it on and left it on 2 red lights for 2 mins and rescrewing it bit by bit but all im getting now is 3 red lights and the code 0002. the copper has become scratched from the spring washers but that had already happened and didn't seem to make a differance