Wrist raise

In addition to what sberman provided, swipe up from the bottom of your watch screen, to open Control Center and make sure Theater Mode is not activated.

See especially “Wake the Apple Watch display” here.

Turn on and wake Apple Watch - Apple Support

You're welcome.

Good catch!

For some odd reason, there have been a rash of these won't turn on wrist raise posts and most of the time it's been Theater Mode. Not sure why so many?