How to charge the batterie separat? USB port in camera ist defect

Hey hi Otward, you might just want to replace the USB port or if just want to charge it separately then you need to tear it down / disassemble the product. Here is the teardown for the battery: GoPro Hero4 Black Battery Housing and Rear Frame Replacement - iFixit Repair Guide

Also, I am not sure if it is the USB port for sure? So if you think that it is not the USB port than you can just buy a new battery and place it in the camera by following the same teardown guide I have given to put the new battery. Beware that even a simple mistake can break your camera and cost you a lot so make sure that you proceed with caution. Thanks for reading and have a Gorgeous day!!!