Apple released a new watchOS update that aims to avoid an issue that causes the watch series5 and SE to stop charging. But if you are unfortunate to be experiencing this problem, you could be eligible for a free repair.
According to the company’s support document, a small number of customers have encountered a situation where the aforementioned watches charge after entering the power reserve mode. The newest Watch OS 7.3.1 is said to prevent this from happening.
If you are already encountering this situation and the update doesn’t fix it, then apple recommends your watch on your charger for 30min.
If the situation remains unresolved, apple suggests you contact apple support so that it can arrange a mail-in repair for you, which is absolutely free of charge.
It is also worth knowing that Apple will examine your watch to see if it’s eligible for the free repair.