Old thread, did anybody ever come up with a solution for this problem? Mine just started doing it.
I had the same problem and i repaired it this morning by doing the following things
Is remove the processor, i then reballed the graphic chip (this is done by removing the heat sink and takin a sheet of alu foil
tear a square in the centre of it and place it over the chip, only the chip on the mother board should be exposed (the rest of the foil protects the
motherboard and the plastics.
gently heat the chip for 3 min with a hair dryer or a heat gun. then allow to cool for 30 min.
I replaced the processor and then the artic silver (thermal paste) on the processor.
i cleaned the fan and the fluff out of the heat sink
The i replace the the heat sink taking care to tighten the screws 1,2,3,4 as the heat sink shows.
Refitted the back plate and replace the battery. Pushed the on butten and Bam, she booted.
Thanks Martin - that worked perfectly.
I put the hair dryer on full heat and held it about and inch and a half away from the GPU.
The hair-dryer overheated and switched off after about 3 mins, but that was enough to do the job.
And thanks for the info about the order to tighten the heat sink screws - I hadn't noticed that.
(...and the hair dryer cooled down and works too)