iPhone 4s - Can't find any wifi network after upgrade to iOS8

[KIT]

My stepson upgraded his iPhone 4S from iOS7 to iOS8. After the upgrade, the phone no longer finds any WiFi networks. Under "choose a network", there is a moving circle witch indicates an ongoing search, but the phone can't find anyting at all. It doesen't matter if we try our own network, or any others, the result is the same.

This is what I've tried so far:
1.Wifi off/on.
2.Tried to promt our own network using the "Other" under wifi. Typed in SSID and password manually, but finds nothing (there are no space in SSID-name og "hidden" network in our house).
3.Restart.
4.Reboot (home + power-buttons).
5.Flight modus off/on.
6.Resetting the phones network settings.
7.Disable wifi networking services (Settings > Privacy > Location Services > System Services)
8.Tried to set custom DNS, but can't do (need an already installed wifi-connection to change this).
9.Reset/upgrade the phone using iTunes (no errors during upgrade).
10.Opened up the phone, and changed the wifi-antenna.
11.Put the phone in the fridge for 45 minutes.

But still no cigar... I'm out of ideas. What's next ot do now...?
The option for downgrade to iOS7 is removed by Apple, and I don't wanna install any russian/chineese jailbreak-software on my computer either!

 

[50ShadesofAndorid]

Ouch.. it really does look like you're running out of options.. Did you try taking your iPhone to the genius bar in the apple store? Chances are, it's a hardware problem. If the Genius Bar can't figure it out, then they usually just give you a brand new iPhone to take home.

 

[KIT]

Ouch.. it really does look like you're running out of options.. Did you try taking your iPhone to the genius bar in the apple store? Chances are, it's a hardware problem. If the Genius Bar can't figure it out, then they usually just give you a brand new iPhone to take home.

Well, we live in the northern part of Norway. Quite a distance to nearest Apple Store...
The phone is also a few years, and has gotten the back cover (backshell?) changed twice (privatly) - and now I've also changed the wifi-antenna myself, witch I suspect says goobye to the Apple guarantee (the WiFi was OK after both jobs).
But the kid swear the WiFi stopped working immediately after the upgrade to iOS8.