Wifi and GPS Problem

Well I dropped my iPhone 4 at&t in water and the mic for video and the wifi stopped working and my GPS started giving very vegue location services. Recently my mic started working but the gps and wifi stayed the same... Recently i took my iphone appart because the LCD connector came loose and i had to fix it... After reasembly i realized my wifi was working but very weak and my gps was the same... So i have two questions... 1. Where are the screws that ground the wifi ive heard they could be the problem and 2. Should i replace my wifi antenna or something else?

PS. I had my phone repaired at some shop and they lost some screws and they lost the pressure/connector thing near the battery connector if that makes a difference.