Hi. I can try to help. A picky point, but one worth asking nevertheless: have you checked the battery?
Also, press and hold the side button FOR AT LEAST TEN SECONDS until you see the Apple logo. If you ALSO see a red lightning bolt icon, the watch needs to be charged. Small devices have very weak batteries.
Finally, you may have to force reboot. Press the Digital Crown and the side button AND HOLD THEM FOR AT LEAST TEN SECONDS until the Apple icon appears. If you see the logo but the watch face is still black after restart--and you HEAR a spoken description instead of seeing one--you have VoiceOver activated, which you must deactivate as follows:
Execute the Watch app on your Apple iPhone.
Turn off ScreenCurtain
Turn off VoiceOver
Please try all of these diagnostic steps and let me know what happens. Thank you so much. Good luck!