I have GoPro 4 black and where one month ago has ceased to join.
The charging connection does not respond even the red light does not light.
Tried to put other batteries and even left on for a long time.
What could be the reason? or how can I fix it myself?
There are some things you can try to troubleshoot the problem.
Try a different USB cable.
Try a different charger.
If charging from a computers USB try a different USB slot.
It's much better to use a dedicated charger than USB.Try a wallwart charger like an apple ipad charger or similar.
If none of those fixes the problem then it is safe to say the cameras charging circuit could be faulty.
If that is the case instead of charging with the camera get a stand alone battery charger.They are relatively cheap and easy to find.
Wasabi and Smartree both make reliable chargers to suit HERO 4 and sell just the charger or charger + batteries at reasonable prices.