https://wccftech.com/apple-releases-watchos-7-0-2-with-fix-for-battery-drain-and-ecg/

Apple has released a minor new update for Apple Watch in the form of watchOS 7.0.2 which fixes two important issues reported by users: battery drain and ECG access in supported regions.

It seems that Apple has finally fixed the battery drain issue for which it was advising users to restore their iPhone and Apple Watch previously. Of course, that was not the simplest of solutions and users were not happy about it. Many users were also reporting that despite the availability of ECG in their region, they were unable to access the app on their Apple Watch. This update also addresses this issue with a fix. After the update, make sure that you open the Health app to configure the ECG app to work on your Watch.