Why my iPhone don´t find net?

Hello,

(First I want to say sorry for this bad english, because i am German and i only copied this text into the google translator.)

I have a problem with my iPhone 6. My iPhone 6 (Sim and Netlockfree) place for a display change no more power. In the upper left corner is constantly searching ...

The SIM card works perfectly with my iPhone 4s, therefore I conclude that from. In addition, you can unlock the SIM card.

I have the iPhone ever recovers, filled with new software, put in DFU mode, set in the recovery mode, Rebooted, the network settings, airplane mode switched on and off .....

I do not know what to do. : (

Because of this I assume that there is a hardware defect.

So I've unscrewed (had anyway no longer a guarantee) and have the antenna cable tested. (The next to the battery connector) Furthermore, I have changed the Lightning charging socket / microphone / headphone jack unit, as many said in the Internet that would have something with the antennas to do and in a Teardown from here as "antenna interconnect cable" designated hardware (sitting between logicboard and camera cover sheet) changed "antenna" on the far left (black metal piece with golden contacts, that have 5 holes for screws).

Unfortunately that didn´t helped. Now I do not go on and find the internet nothing that could help me. Where the GSM antennas are for everywhere in the iPhone 6 exactly ???

'What could be broken ???'

If anyone has a clue, I would be very happy about an answer.

What should I do so that my iPhone will has a signal??

A repair with a dealer that is very expensive.


Thanks alot