you are 100% right i called att , they sent another phone out, said i will pay for this phone that i bought 14 days ago and the one they are sending if they see water, they have no clue on what they are taking about . there is no water , i live by the beach , humid all day long. So i called samsung they said take out the new update ! Samsung knows the problem. if you call them , give them the numbers on your phone they put it into there data base on having this problem, im sure a fix will be coming soon.
I have also been encountering this issue with my S8+ - I do use wireless charging at home but it renders Android Auto completely useless. Funny (or maybe not funny) thing is that my WiFi S3 tablet took a software update last night. This morning, the tablet wouldn't charge because of "moisture in the USB port".
Neither of these devices have ever been anywhere near water. Seeing the same thing on the tablet after the update confirms to me that this is software related. I just wish Samsung would acknowledge and let us know that a fix is on the way. It would save a LOT of useless time doing factory resets and sending devices in for warranty repairs.
Switch off phone. Switch on phone, as soon as the word SAMSUNG starts to appear insert charger. Phone should now charge.......it WON'T get rid of the error message but at least the phone charges.
Works for me