Hey @spuddywuddy ,
The first step would be performing a Soft Reset on the phone. To do this press and hold the Power and Volume down buttons for 10 seconds and if a warning pops up, press the Volume down button.
Make sure that you are using the official Samsung charger and cable.
Check the charger port for any dust/dirt/obstructions. If this is free of obstructions, try charging through a different mains socket to check if the issue is with the phone or the charger itself.
That is fine. The next step would be having the phone examined by one of our engineers. Please contact our Support Team:https://www.samsung.com/uk/support/contact/or take the phone to your nearest Support Centre: https://www.samsung.com/uk/support/service-centre/
I have the same problem , phone was sitting on table charging when all of a sudden moisture detected error came up , has not been anywhere near moisture and now can't charge it unless I but a wireless charger.
First ever Samsung phone and must say extremely dissapointed.