It sounds like you have replaced pretty much every component that could be causing the issue. Have you verified that your router is working correctly?

Otherwise, sometimes the oils on your hands can interfere with the wireless signals. Make sure all the components you handled are cleaned off. I little bit (emphasis on "little") of screen cleaner or even Windex will do.

I had an iphone 4 in for repair last week and compared parts on it to the parts on mine. Specifically looked at the EMI shield and mine was missing what turned out to be a crucial piece. I actually found it and replaced it and now my wifi is back. I did order another complete EMI shield in case that happens again - cost only $12.

I think I know what you're talking about. I remember seeing a metal piece on that shield that the screw goes into. It must have fallen out as I don't see it. Where did you order that EMI shield from?

Hello :-)

I Search the EMI shield in the near of the battery connector, i Found only One Store an there is it out of Stock ...

I ordered mine from Parts4repair.com, sure is taking a while to get over here.

http://www.parts4repair.com/products/iPh...

i hope its helps, the signal antenna its the back glass top, when you remove the screw on the battery connector the oil on your hand affect it, so what you have to do (for me works) its clean the little metal that makes antenna together with the back top and the top, try it, it improved signal on my iPhone 4

I had the same problem and i found the answer was that the little metal clip wagon the black wifi protector was missing. I ordered one from China for $2.55 and replaced it and it works fine!!

you can buy it at http://www.dealrepairs.com

very low price,free shipping.