Sounds to me like the charge port may be bad, I've run into this issue several times and a charge port replacement always fixed the issue.
Phones can be weird especially since they have so much tech nowadays. Phones are most susceptible to moisture than anything else, taking it into the bathroom while you shower can cause moisture exposure or even damage. This may be what happened I'm not sure but the solution for sure would be to replace the charge port. Or replace the device.