Apple Watch Series 7 not charging and overheating after surfing

The Series 7 Apple Watch is showing a red charging cable when trying to charge and won't charge. Other searches suggested that it means the battery is critically low. The Apple Watch will not restart when holding both side buttons and will not charge even after 24 hours. The Apple Watch was left on charge for days, and things still haven't changed. The Apple Watch only started doing this after completely dying while surfing. Also when recently trying to charge it the Apple Watch started overheating and showed thermometer icon. What should be done to fix this?

[Re-Titled by Moderator]

Original Title: Apple Watch critically low