Mine has done the same. (Again!!) My current watch is 10 months old and was a replacement by Fitbit for my previous Sense which did the same thing at about 12 months ago. After going through all the steps last time, I received a free post pack to send the watch back to Fitbit, and they duly replaced it. I have screen shots of last sync showing it was charged, but black screen persists and cant turn it on - no vibration when pushing the button, despite many long attempts
