iPhone 4 - Poor recepetion and wifi.

Hello,

I purchased an iPhone 4 off a friend. After closer inspection it appears the phone has been changed from a black to a white case (unsure why). Anyway the reception usually sits at one bar, searching or SOS only. Wifi does not work either unless I am within 2-3 metres of the router.

I did a quick teardown of the phone and noticed several screws were missing (see picture).

The circle in the top was not actually missing a screw but missing the metal 'plate' that sits underneath (I tried replacing it with tin-foil but it did not seem to help).

Edit: The 'blue coil' near the bottom of the logic board also SEEMS to be 'damaged', although I am not entirely sure.

I have just upgraded to IOS 6, and performed all different kind of resets, fresh out of ideas. Anyone have any direction how I could fix this?