Battery and charge port changed, still won't charge?

"The iphone wont charge because of an issue with the U2 IC chip on the motherboard. To repair this, you need a professional to either reball the chip or replace it (Replacing is always better).

This is why your iphone will not sync or charge even when the battery and charging ports are replaced. This is a very common issue. If you have never soldered micro chips before, I suggest you find someone that can."

i have some problem once on iphone 4,i change and replaced charge port and battery double time.but i wont charged. when i recheck,charge port and battey cord is correct voltage on digital meter, Then i change the "usb cable" and "charger adaptor" it was fixed.

Maybe a long shot, but have you checked for any bent pins where the charging port plugs into? Or any corrosion/lint/dirt on the usb cable which plugs into the charge port?

U2 IC is probably damaged. Don't try to replace it if you don't have the skills and equipment.