USB-C Thunderbolt does not work after spilled liquid

You can probably tell just by looking if it’s the port. Try looking with a flashlight and see if you spot any corrosion. Otherwise, you’ll want to open the machine up and see if there are any signs of liquid inside. You can remove the ports pretty easily and just see what they look like. If there’s corrosion on them, but internals look clean, probably just the port. You might even get it to work if you clean up corrosion with some isopropyl alcohol and a cotton swab. Depends on what the actual issue is. Liquid damage in the port can cause electrical damage to board components, but I have seen lots of these that are just the port itself.