I cut my Apple-repairing teeth on an iBook G3 that would lose its BGA-soldered GPU if it overheated. The "fix" was to use a heat gun, propane torch (my choice), or even burning alcohol to gently reflow the solder:

https://forums.macrumors.com/threads/repairing-ibook-g3-grap...

I did it at least three times before that laptop died. Fun times.