iPhone 4 wifi connectivity dramas

Gday,

Ive currently got an iPhone 4 that I cant for the life of me get wifi connectivity out of. Ive spent several hours researching/troubleshooting but to avail.

The switch works on the software and will turn on/off, but after the "searching" symbol does a quick flicker then nothing. I have an iPhone 5 and 3 PCs all with full strength next to me so its not signal strength.

Things I have attempted;

- reseated the 4.8mm screw

- the U shaped metal contact around said screw is intact. I also placed a small piece of tin foil underneath to guarantee contact.

- Reset network settings repeatedly

- Upgraded firmware to iOS 7.1.1

- Note that the 1.4mm screw that sits next to the top left corner of the battery has had its internal thread chipped off the board. As such, I placed another piece of tin foil between the antenna plate and thread in case any connection path had been broken, given no screw is seated there.

- Also note that im running the phone without a sim card, just need it for wifi.

By the looks of things, it would appear to be a hardware issue as its not even contemplating working, but im open to any other suggestions of areas to look/ things to try no matter how outlandish as im at wits end.

Cheers in advance