Please confirm that you did get a message that stated there was no water damage. Do you recall its exact phrasing? Typically there is no assertion message popping up when a phone isn't wet since that's the normal state any phone should be in, the moisture sensor will only getting triggered when it does detect a problem.
Or are you instead referring to the LDI (Liquid Detector Indicator) on your Pixel by the SIM card slot? If that is what you're relying upon, since the battery isn't actually getting charged perhaps its just a coincidental, one-off glitch. Have you at least tried restarting your phone?