Battery not working after water damage

Packed my fully charged MacBook Pro (powered off) for an airline flight. Wasn’t thinking and put a water bottle in the backpack with the MacBook. Thanks to air pressure, the water bottle leaked a bit. After landing, I noticed the water bottle had leaked and the outside of the laptop (top and bottom) was wet. I wiped it down and didn’t really think it was enough water to cause any damage. However, when I tried to turn on the MacBook, it would not power up with the battery. I plugged it in and luckily it powered up and seems to work just fine. However, if you unplug it, it dies instantly. So, obviously, the battery appears to be fried? The battery level says it’s at 92% and does not change. It had a great battery life before the incident. Maybe water got into the USB, charger attachment or other side “holes".” Any ideas on a cost effective fix? Since the device is 6 years old, I don’t want to take it into Apple and spend a bundle. I’m not super techie, but can maybe try to fix it.