Maybe you could try cleaning it. If it has never been opened then there would be a lot of gunk inside (dust, tar if you are a smoker, lint...) and a water ingress will make it all soak and stick to the board. All the worse if the water was dirty. I would open it up and try to clean it as well as I can. A dry, soft tootbrush to brush off all the dried gunk and then cotton wool on a stick soaked in isopropyl alcohol to clean the residues. You do not need to dry it in rice afterwards, just air dry it for a few minutes. Or hours to be safe. I cannot promise it will do the trick, the damage has already been done. But for the same reason, you have little to lose.