Apple Watch SE glitching then screen went black
wearing watch when it was very hot out. Watch began to glitch. Watch charged overnight, but now screen appears black even though it's on. Voice over and screen curtain are off.
Apple Watch SE
If the watch got overshot, then there might be a problem with the battery.
Your best option may be to make an appointment at the Genius Bar in an Apple Store near you and let them look at it. If that is not possible, use the online Apple Support option. Either way:
Genius Bar Reservation and Apple Support Options - Apple