So I had a Samsung S6 that would not charge, when you plugged it in, the white lighting bolt battery symbol came on but no charge led light. I suspected the charger or cable, but that didn’t help. I fast came to the conclusion it could be the USB port.
I then found some posts about ‘hard restarting’ the phone, by holding the home and power buttons together, it seems to work for some, but not me.
Next was factory resetting the phone, by holding the home, volume up and power buttons together, no luck with this either. By this point the phone had no charge left at all, so it could be this may have helped but it was too little too late.
Next up was to try a wireless charger, yay! The phone started charging and is now working once more!
Hope this helps you!