Normally I would default to a software problem with this sort of fault, but if you cannot actually turn the machine off, that could make fixing it difficult. When you press the power button do you get any response? Does the display shut off at all? What sort of issues were you having previously? (Sorry for the barrage of questions, I just tend to ask them all at once to avoid endless back and forth )
It is starting to sound to me like this may be a hardware issue, assuming you have already tried things like SMC or NVRAM reset. It may be time to have a look at your MacBook’s innards (or have someone else look) I am wondering specifically about the power button area since you don’t seem to be getting a response from the button.
This model has a small daughterboard which the Touch ID button connects to and I have seen little bits of liquid get in there more than once and muck things up or just make machines act really weird. It may also be worth opening, just for the sake of disconnecting the battery if nothing else, since that will forcibly reset the SMC.