I fixed a 2008 macbook with a GPU issue (wouldn't boot past BIOS) by turning it on and letting it run full-tilt under a blanket. Eventually it just resoldered itself.
It didnt. 8600M had a design defect in microbumps connecting die to package. Thermal cycling in high heat scenarios (Apple is famous fo cooking components at the margin of T-junction) softened improperly selected underfill and broke microbumps connecting die to package. Repeated heating up can again soften it to release stresses and temporarily reconnected broken traces. It never fixes the main issue of broken chip.
>On July 2, 2009, the date being ironically a year after the notorious 8-K that publicly kicked off bumpgate, the company put up a job listing for a “DIRECTOR OF PACKAGE TECHNOLOGY”.
https://en-academic.com/dic.nsf/enwiki/2011837#Problems
https://semiaccurate.com/2009/08/21/nvidia-finally-understan...
>On July 2, 2009, the date being ironically a year after the notorious 8-K that publicly kicked off bumpgate, the company put up a job listing for a “DIRECTOR OF PACKAGE TECHNOLOGY”.
https://notebooks.com/2008/10/10/apple-to-replace-faulty-nvi...