Watch doesn't turn on
My Apple watch would not respond to a hard reset. I pressed Crown and slider for 10 seconds, release after logo appears, but that doesn't help. Still can't turn it on, just see blinking logo
Apple Watch, watchOS 4
Try draining the battery completely. When you recharge after that, is it coming back to blinking logo even then?
Here is some further guidance too:
If your Apple Watch won't charge or it won't turn on - Apple Support
If the issue persists, best to take contact support then: