@chris_cookie yes water resistant but not water proof. What you have is a water damaged device. Time to treat it like that.
The very first thing you want to do is to stop continuing to try to charge, sync or otherwise use your phone. This potentially can make a bad situation worse. This may further damage your phone.
The next thing to do is to clean it. Disassemble your phone using these guide [[Topic:iPhone 11]] . You must remove all EMI shields. If you do not remove those, you might as well not do anything. After you remove those, clean the whole board, connectors and all, with +90% isopropyl alcohol. Follow [guide|5825|this guide] , and even so it was written for a 3G all the points are still pertinent to your phone. While you clean your board, check for any obvious damage, like burned or missing components etc. When it is properly cleaned, replace the battery. All these steps are to avoid delayed failure caused by corrosion. Best thing to do would be to clean it with an ultrasonic cleaner, but if you do not have access to one, this will at least help. Once all this is done, reassemble your phone and reevaluate. Until it is cleaned, everything will only be a guess. It is possible that you have a bad LCD as well as a damage Lightning connector assembly and replacing those may fix it. Even with all this, water damage has only a small chance to be fully repaired, but at least you can give it a try. If not sure about all of this I’d try to contact experts like @refectio or @imicrosoldering and see what they recommend.