Q: Dead WiFi button!!!

I have the same issue as some other users. I have tried all the obvious solutions but it still wont allow me to activate the WiFi button. All phones OK and wife's i pad air OK??

Tried it while on charge, off charge, close to the router but still no luck. Even tried to tether with the iPhone but no luck. Its about 4 years old but still in good condition. Has the WiFi chip packed up??

Any more ideas please. Im thinking its time to renew!