iPhone 4 wifi problem

Well i have two iphone 4 (One is busted, whenever you plug it it in shows the apple logo then turns off, loops like that)
But before that phone (the looping one) had great wifi, while the one i'm using now is pretty ****(cant grab any bars, have to be 5-10 feet in range of wifi box)

Now i've tried the tight the screw method but that didn't work, i put some tin foil under the little thing(the little metal clip that touches the little gold dot on the phone) Nothing.


I was wondering if i could swap whatever grabs the wifi from the busted phone to my good phone?

 

aaaahhhhhhh, i replaced the logicboards to the other phone and nothing, still no wifi!

i'm getting really annoyed, anybody have any tips?