Chosen Solution
i did a speaker changing just now, and after finished working with the unit, my right I/O board is not working (USB port is OFF) i think i broke one of the cable that is attached to the I/O board, i post an image here, do you guys happen to know which cable is in charge of supplying power or connection to the I/O board?
@aaron75 sure looks like the ends got chewed up on the cable. Just by the way it looks you also want to check the connector on the I/O board carefully. Make sure that it does not show the same damage. The cable itself should be this one MacBook Pro 15" Retina (Late 2013-Mid 2014) I/O Board Data Cable - iFixit Store Apple part number 923-0666
Both cables are for connecting to I/O board, but for different types of things. It looks like power lines go mostly through the flex cable that goes over the fan. But lots of the USB data is transmitted through the other cable, that goes underneath, that connects with the locking lever type connector. I’m not sure this would have that great an effect on the functionality of the USB port, but the clips that come off the top of the ports should be tucked underneath this lip along that side. It could just be that the alignment on the port isn’t quite right so things aren’t making proper contact even though you can insert a USB device.
