Hi, my friend smashed his iPhone and wanted me to repair it for him as I have done it multiple times before. When I removed the back cover I found out that the antenna and battery cables are ripped off, so I have replaced both of them. The battery works fine, but the phone was keeping searching for network. I thought that maybe it was the after market antenna so I replaced it with one from an working iPhone (and put the aftermarket one in it and it worked fine, so no problem here) and it was still searching, therefore I started to think its a software fault. While connected to my wifi, I have checked if the date sets automatically, tried cycling the air plane mode, then restored the network settings, then the phone, then updated to iOS 7.1 and it still keeps on searching. The phone shows IMEI and ICCID. Are there any other option other than replacing the motherboard?

UPDATE:

So I tried swapping logic board from another iPhone and it worked, so the problem is on the logic board, although I do not know if it is a software or hardware fault. But I tried disconnecting antenna on a working iPhone and it had the same issue as the damaged one. Therefore I am guessing that the problem could be the antenna connector on the logic board as the mating half of the antenna was torn away, so maybe the connector was damaged as well during the fall. But I really

This is the best picture i can take now, if anyone is still interested in solving this case i would be more than happy to take more pictures of the area