This one is really strange. I got A1398 which is working perfectly fine except right side USB port, which is working partially - it recognises external flash drives, USB mouses or even boots and works from external drive OS, but the problem is, that it doesn't recognise iPhone at all. AMP meter shows 5V but 0,03-0,05A of drain when phone is connected (it won't recognise phone with AMP meter disconnected too). If I connect 2,5" HDD over adapter, it takes 0,79A, then drops to 0,12A and doesn't recognise it. But if I connect the same drive without AMP meter drive is recognised and works OK. I have already replaced I/O board and both flex cables, but with no success. Connectors on motherboard look perfect, no corrossion or damage. Other side USB port works completely fine with all devices I connect to it. I thought it could be power problem, but it keeps 5V stable on board. Maybe it's PCH protocol problem?