On the support page, Apple explains how to check if your Watch Series 5 and Watch SE is facing this issue. “A very small number of customers with Apple Watch Series 5 or Apple Watch SE models running watchOS 7.2 or 7.3 have experienced an issue with their watch not charging after it enters Power Reserve,” says Apple on the support page.
“To check if your Apple Watch is affected by this issue, place your Watch on the charger that you normally use, then wait at least 30 minutes,” Apple explains.
After 30 minutes, if your Apple Watch still won’t charge, contact Apple Support to set up a mail-in repair free of charge. “Your watch will be examined before service to verify that it’s eligible for free repair,” notes the document.
Apple has also released watchOS 7.3.1, which prevents this issue from happening to other Apple Watch Series 5 or Apple Watch SE devices.
To update your Apple Watch to watchOS 7.3.1, follow the simple steps. Open the Settings app on the Apple Watch and then find Software Update. Tap on it to get the latest watchOS update. Otherwise, you can also install the update through the Apple Watch companion app on your iPhone.