Apple Watch stuck on erase all content, side button sometimes long pressed by itself

If you've got this problem, you know it.

Any progress anyone? The last thread died because no new replies.

So far, what I've gathered is:

1. The guaranteed way is to let the battery power died. Plug in the charger and it will move to pairing mode (mine did 4 days ago and I successfully updated to watch os 6, apple watch series 1). Today it restart by itself and enter the loop again.

2. No clue as hardware of software issue. My hunch is hardware.

3. Is everyone stuck at around 75% (9 o clock) at the erase all data? Mine did. I've looked around and maybe it's safe to assume everyone does.

4. No recall or repair from Apple so far (I had this problem since 2 years ago if I'm not mistaken). Really few threads about this problem and the ones which have lot of answers have died.

Hopefully someone from Apple can answer this and please no need to put guide to force restart etc.

Thanks a lot!