DIAGNOSIS The main control board is working (it's still cooling), but the segment display on the front panel has failed or lost its connection. This is usually a loose ribbon cable or a faulty display panel.
FIX Unplug the unit. The display/control panel is held by clips or screws from the inside. You'll need to carefully remove the plastic trim around the door (it usually pops off). Once you have access, locate the thin ribbon cable connecting the display to the main board. Unseat it and firmly reseat it. Reassemble and plug in to test.
IF THAT DIDN'T WORK The display panel itself is likely dead. You can operate the cooler without it—it will typically default to its last set temperature. If you need the display, you'd have to source a replacement front control panel assembly.
HEADS UP Be super gentle with that ribbon cable and its connector latch. They're fragile. If the latch breaks, the connection will be intermittent, making the problem worse.