My buddy gave me a laptop a while back that kept getting really hot and randomly turning off. After doing some research I determined it was the fan vent blocked with dust/debris causing the laptop to overheat. So I decided to disassemble it to clean the fan vent. Now I had built a couple of PC's before but never taken apart a laptop. At one point I had no idea where to find any more screws and couldn't figure out how to get it apart further without breaking it. Luckily I found a handy YouTube video on this exact model showing where all the screws were and how to fully disassemble it.
So of course you know that the fan is the ABSOLUTE LAST thing to get to.
When I got to the fan I noticed an oddly coloured foam pad before the outtake holes. Upon closer inspection it was a mat of dust/debris/dog hair etc. Now my buddy and his wife keep a very clean house (much cleaner than my place) so they were horrified when I showed them the pics. After I removed that clump of debris and reassembled everything the laptop worked fine for at least another year or so.
Not sure why they can't just make laptops with a couple screws to remove the fan from the outside to make it easier to get to and clean. Oh yeah ... then the service guys wouldn't make all the money for fixing such a simple thing.