Silly question but you don't still have a protective film covering the screen? These can have trapped air bubbles under them which show as small white dots.
Stuck pixels wouldn't normally show when the screen is off.
Samsung Galaxy S8 review
1995-2015: How technology has changed the world in 20 years
This poetic animation about monsters is illustrated in a Van Gogh painterly style
How to get WWDC 2017 tickets
Synology invites you to visit them at Insomnia on 26th – 29th August. Book your tickets now and visit Synology.