Ok. So this has happened to me already 4 times and technique below is not guaranteed at any circumstances. However, it worked for me all the time. So what is the issue? iPhone 4s simply stop providing me wifi feature since I updated the iOS to newer version. It has happened with any major iOS update 7.x, 8.x. Wifi was working perfectly fine, then I updated iOS and boom – wifi button grayed out. Soft reset, hard reset, factory restore, nothing helps. Apple support claiming it as a hardware fault.
Ok, let’s take a hair dryer, turn it on and smash earphone of the iphone with the heat until it “melts” or at least shows you it is overheated and it’s turning itself off. Great, we’ve?just melted the wiring and it’s time to put it in freezer for quick cool down. After 5-10 minutes I am taking it out, letting it dry off with cloth. 5 minutes later I turn it back on and VOILA – here comes the wifi feature again until next iOS update.
Hardware fix applied to software issue? Science fiction becomes reality :).
WiFi grayed out (not working, image on left) vs WiFi ON (working, image on right)