No service with an exclamation poin, can't get it activated

Hi,

I was wondering. I got a iPhone 6 that gives the message “No Service” with an exclamation point in a black triangle. I read about a lot of different reasons why this could be happening.

For me its not important to get the phone repaired so that i can use it to call with it or anything. I am a UI/UX designer and i would love to use this phone just for my prototypes. But when i try to activate the factory reseted phone it gives me the message “Activation failed” there is an update required to activate your iPhone. For more information check http://support.apple.com/HT201222. Just before the message it flashes to the screen where the iPhone tries to get activated and it immediately goes to the failed message.

After that the phone restarts and i get the same issue all over again. I tried different sim cars, i tried activation through iTunes and whatsoever. Oh and when i connect the phone to a Mac or Windows iTunes is doesnt show any information of the phone. It shows its connected , but i dont get the usual options. I have updated the phone to the latest iOS through the recovery mode function. The phone has been connected to multiple Wifi’s and i dont know how to go on.

So does anyone know how to activate the phone or is there a tool that can simulate it so that the phone will go into iOS.