Wi-Fi Problem. Everything in the right place. Could be the chip?

The iphone (ios 7.1.2) was dropped in water but everything works fine except Wi-Fi. I have poor signal and it can;t find more than 2 networks. I checked and cleaned a 100 times everyting. I tried with a new screen, a new wifi antenna, new screw, new speakers ( i took them from a perfectly working iphone). When i replaced the motherboard, wifi worked normally.

The copper dot from the top of the motherboard looks fine.

I've noticed that if if the long screw isn't there, the signal is just one dot, and if i put it back, i have a dot and one bar (without the first bar) from the same place in the room. I restored it assuming that it was a software problem but it didn't fix it.

Could it be the Wi-Fi chip? I mean, it could be broken just a little bit? From what i know, chips broke down for good or they work entirely.

Sorry for mistakes. English is not my native language.