Bent iPhone 6 searching for signal

Hi everyone

My friend bought an iPhone 6 a couple of months ago. After a couple of weeks, he accidentally droped it between his car door when he was closing it... The iPhone was bent. He gave it to me and another friend of mine took everything apart and bent it back. The only thing 'broken' was a blue circle in the middle of the screen (barely noticable).

So it worked for a couple of days, but suddenly the phone said 'searching' and 'NO Sim' etc. So we tried repairing it, no solution. My friend bought a new iPhone 6 and the broken one was is still in my room gathering dust.

Now I want to try to fix it, because my iPhone 5 is dying.

Do you guys have a fix? - So the iPhone was bent back to his original shape, worked a couple of days, but now it gives or the searching message or no service/sim card.

(my friend said it was the system board that was broken or something.)

A fix would make my day and it would be a great start of 2016! haha.

BTW: Wifi works, I don't know if that is the same antenna?