Chosen Solution
My phone permanently thinks there is a USB device connected and is trying to charge it. This causes the phone to not recognize when a power cable is plugged in and prevents charging. However, I can charge the phone after a few tries while it is turned off. I figured there was a short in the USB-C port so I replaced the I/O daughter board (twice actually). Either I am getting bad parts, or this is not the problem. Any other ideas on what might be going on?
I’m not familiar with the s8. But most phones have a charging ic chip(with iPhone for example it’s called Tigris and a communicating chip called tristar). Sometimes a charging ic can be damaged,or go bad. This can cause problems. Have you tried factory resetting it(back up data first)? Did you use a crappy charger and cable with it recently? Does the phone get warmer than normal? I know that mark Schaefer with iPad rehab works on Samsung phones on a microsoldering level. You could always contact them if you can’t figure it out. But if you’ve tried factory resetting it to run out likely software issues,then it’s got to be hardware related. If it’s not the charger port,it’s probably the charging circuit.
