Screen problems
Most screen symptoms — a black or offline screen, new content not showing, no sound, or a YouTube error — are triaged in Something's wrong? Start here. This page only covers a few specific picture and timing quirks that aren't on that list.
The picture flickers, or the colours look wrong
Usually the cable, not the screen. Reseat or swap the HDMI cable and check the TV's input.
There's a black flash or gap between videos
Turn on gapless in the screen's settings. On a video wall, set it on the main (master) screen — it controls the others. See Device settings reference.
The screen turns on or off at the wrong time
Check the on/off times and the time zone — a wrong time zone throws the timer off by hours. See Set working hours so screens turn on/off automatically.