It has been discovered that the Apple Watch lacks a user-accessible recovery mode. What this means is that if you were to upgrade to a newer build of watchOS and don’t like it, downgrading to an older build is almost impossible for the regular user. This means that you will need to send the watch back to Apple who will then charge you as it is considered an out-of-warranty repair service.
Why is this an issue? Well if you might recall, Apple released their first update to watchOS a while ago. The update was meant to introduce improvements to the watch’s software but it was later discovered by users that the update kind of messed up the heart rate collection feature in which it became less frequent and erratic in their collection times.
In such a situation, rolling back to the older build would have “solved” it, but like we said given that the Apple Watch lacks a user-accessible recovery mode, that would not be possible. That being said Apple claims that the heart rate recording was not a bug but rather a feature. In any case it is possible that there might be a way to access the watch’s recovery mode, but until now it has yet to be discovered.