DIAGNOSIS The control panel lost power, but the main unit is still getting juice. This points to a loose internal connection or a problem with the display board itself.
FIX Start with the simplest thing: a hard power cycle. Unplug it from the wall, wait 2 full minutes, then plug it back in. Listen for a beep and watch for any flicker on the display. If it comes back to life, you're good.
IF THAT DIDN'T WORK The ribbon cable connecting the main control board to the front display panel might have come unseated. Fixing this requires removing the top plastic shroud, which involves taking out several screws and carefully prying clips. If you're not comfortable with that, it's a service call.
HEADS UP If the display is dead but the unit is still dehumidifying (you can feel dry air coming out), it's probably still working but you can't see the settings. Don't assume it's off—check the bucket so it doesn't overflow.