How to fix a water-damaged Apple Watch that won't turn on?

I have an Apple Watch Series 6 that I took to the beach. I swam a bit with it and then went on a boat ride. After that, the watch stopped working, showing a thermometer and then the screen completely shut off. I've tried force-restart by pressing the crown and side buttons at the same time for a while and nothing. I've left it alone for days and then charging it, which seems as if it would be turning on because it shows the Apple logo, but then goes back to the thermostat flashing a couple of times and then the screen shuts off again. Has anyone been able to overcome this? I'm almost at the point of admitting that it will never work again.

[Re-Titled by Moderator]