The Apple Watch is stuck on a black screen and won't turn on even when you tap the screen and press its buttons.
The most common cause of an Apple Watch that won't turn on is that it's run out of charge. Place your Watch on its plugged-in charging "puck" and make sure the magnetic side is attached. You'll know it's charging when the screen displays a charging symbol.
Confused? Apple has a great support article on Watch charging.
If your Watch is charged but still won't turn on, watch the following video:
For other troubleshooting steps, check out Apple's support article on the Watch. If you still cannot resolve the problem, contact Simplifeye Support.