xbox turns on then off right away

Sometimes even having metal washers period can short the mobo, take off the washers and the screws, just put the hink sink ontop of the chip, apply very little pressure withyour fingures and turn on the xbox. Also before all this clean the chips very well, get all of compound that is around the chip off too. Reapply it and just sit the heat sink on top of the chip it little pressure added.