What's behind the "hairdryer" fix for broken iPhone 4s WiFI? So for all of the iPhone 4Ses that got the grayed out WiFi problem after upgrading to iOS 7, the only fix that seems to actually work is basically heating up the iPhone up (till about the point it gives a heat warning), then chilling it, and then restarting it. (I've seen this solution in various places, such as this Apple Discussions thread).

But what exactly is happening? Is there still a physically damaged WiFi chip in these devices that the software has been tricked into using? Or is it a weird work around that tricks defective software into working properly?
I have tried this fix and it does work although it wasnt permanent.
The only thing I can think it is doing is re setting the base temps of the motherboard and chip, much like a PC. In other words the software might be looking for the difference between the motherboard and the chip temp. 
If they have set this too low for the 4S then obviously it would show it is overheating even if it isnt.
By heating up the motherboard and the already hot chip (which wont heat up further as much) you are re setting the parameters and so it works for a while or permanently. I'll try further.