We've had a couple of 100-degree days here in NYC, and the only thing that deals with heat less well than me is a laptop. If the CPU isn't kept cool by the cooling fans, the whole thing shuts down. And if you don't keep the fans clean, the accumulated dust and gunk can cause the fans to crap out.
Here with help is crazy Canadian ElectroBOOM, a/k/a Mehdi Sadaghar, who shows you how to troubleshoot or replace your cooling fan. "Repairing a laptop may sound like a brain surgery, but in fact it is more like a nose job if you are careful," he writes. I won't warn you as to where the laughs are in this video, but I will say not to drink coffee while you're watching it: