I know what he is doing....basicly, you did the x-clamp fix, and put it together before testing it, right? Now, after all is said and done (did the fix, put it together, turned it on) it still gives the rrod?
The first time I fixed mine I did the exact same thing, and had the exact same results. here is what I did.
With the unit fully assembled, I completely wrapped the unit in a towel BUT left the front unwrapped, so 5 of the 6 sides was wrapped, and so I could watch the leds and manually feel how hot it was getting.
Now, with it wrapped like that, I turned it on and every 30 seconds or so I would place my hand on top of the unit (between the 360 and towel) so I could feel how hot it was getting. I did this for about 2~4 mins (NOTE: the unit never overheated, didnt let it get that far). When it felt that it was getting rather warm, I turned it off, unrapped it and let sit until it was fully cooled down. ever sense then the most I had to do to mine was to take the bottom case off to re-tighten the black screws. other then that it has worked like a champ.
WARNING:WARNING:WARNING!!!!!!!
Please keep this in mind about using the towel trick....if you go to far with it (let it heat up too far), it can cause more damage to your 360, possibly to the point of no return.