Display, touch and standby troubleshooting

Distinguish screensaver, screen-off and standby while diagnosing touch or display failures.

Symptom	First check
Screensaver visible	First touch dismisses the animation
Audio plays with black screen	Screen-off idle stage in Display & power
Standby	Briefly press the physical power button
Faint backlight	Some display revisions cannot switch it off
No UI	Display profile or UI service

Check display model, revision, profile and cables. HDMI touch screens with separate USB touch require both cables.

Read-only SSH diagnosis

systemctl status mupibox-ui --no-pager journalctl -u mupibox-ui -b --no-pager -n 100

Screensaver computations should stop in screen-off and standby. If CPU load remains high, report the idle stages, NG version and logs.