Samsung knows about this issue and requires the device be sent to their facility. There is no walk in facility/store anywhere near me. They do not care that I will be without my phone for several weeks after having to mail it to them. They do not care that I am disabled and need my phone for safety reasons. I will switch to Apple products even though I prefer Android devices. I spoke to them (and At&t) extensively and could barely even get the agent to understand the issues because I couldn't get anyone who speaks English well.
If your having a moisture issue this is because your in a area with too much moisture, typically when water or moisture goes into the charging port the note 9 will prevent you from charging it till it is fully dried typically it can take about 5 to 24 hours for it to fully to dry and that error will go away..if it persist send it to Samsung but Samsung can't do anything beyond do their magic, Samsung is a powerful company and is one of the best out their, but if they are not willing to assit you in anyway then you can die a law suit against them!
The 9 series and 8 series note has this issue my S9 plus had it only when i restarted the phone plugged into fast charger i cleaned the port of lint and it was back to normal although . The down fall to buying a phone through samsung vs buying from AT&T is samsung wants to fix the phone but AT&T will replace the phone and have it mailed to ypu and you mail the old one in after you get it.