I see that you have no proof or explanation to your alleged reasons for the Wi-Fi greying out, but if you research other sites, they have confirmed it is a hardware failure with the Wi-Fi chip, not batteries, SIM cards, firmware or software causing the Wi-Fi chip to become disabled.
Many have fixed the problem by re-working the solder on the Wi-Fi chip, or heating up the iPhone with a hair dryer.
Apple's advice is to reset the network settings. When that doesn't work, restore the iPhone. When that doesn't work, contact Apple so they can tell you it is a hardware failure. The majority that have the problem also confirm software reset and restore does not work.
I don't need to present evidence. I was simply pointing out that just because it didn't fix your problem doesn't mean the info to set up as new wasn't helpful to others. You seem to think only on thing could possibly cause an issue. I repair iPhones and am an ios certified technician. I know what I am talking. about because I have repaired hundreds of them. How many have you repaired?