My phone started having an error while being charged. Message will pop up that moisture has been detected even though I've been careful with it. It started after the latest system update. Not sure what's going on.
Reboot your device to recovery mode. Turn off device then turn it on while holding volume up button. Let go everything once it turns on or once you see the Samsung logo. from the android recovery highlight wipe cache partition using volume button and select it using power button. Once done highlight and select Repair apps if applicable if not go ahead and select reboot system now.
If it didn't fix the issue try to go to your Settings > Apps > Hamburger icon or the one that looks like a tower signal icon next to the word " Your apps " then enable the System App/File then hit " Ok ".
Find USBSettings or similar then select Storage > Clear data > Ok and then go back then force stop. Restart your device and try again to charge your phone see if you will get the error message.
If still didn't fix it. Back up all your files and factory reset. If still persist go to a authorized repair by Samsung or you can call Samsung directly. Hope this helps!
I know how frustrating this is. I've had it happen myself. I understand that you stated that there has been no contact with any type of liquid. However, I am including a couple of articles that would address this issue.
If you are still receiving the pop-up, I would recommend having the phone evaluated by a certified technician. You can find the nearest authorized service center using this link: https://www.samsung.com/us/support/service/ or contacting customer support at 1-800-726-7864.
