Can't relaunch/use finder on a 2019 MacBook Pro The finder app on my new 2019 MacBook Pro is unresponsive and if I relaunch it then nothing happens.

It's a newer MacBook and thus the power button is the touch ID button. I tried to power off the MacBook by holding down the touch ID/power button but that doesn't work.

I also let the battery run out hoping that that would power down the machine but it appears to only go to sleep.

So how can I fix finder on this new touch ID MacBook pro that I can't seem to shutdown.

..and of course I can't shut it down via the apple logo in the upper left.
When you relaunch Finder, are you doing this from the Force Quit Applications menu? If you haven't done this, try pressing command+option+esc keys and the Force Quit Applications menu should pop up, then relaunch Finder from there.

If this fails, you can also try force a reboot by pressing Control+Command+Touch ID/Power button keys.

If this also fails, and you have access to Spotlight, search for the Terminal app. Once in Terminal, you can force a reboot by typing sudo reboot. It will prompt you with your password, but it won't show in the terminal window as you type it. Just hit the return key when you've finished typing your password and it should force your MacBook to reboot. 

Hope this helps.