As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW RECEIVED A DISPLAY COOL CAUTION MESSAGE. FOLLOWED QRH, DECLARED AN EMERGENCY AND RETURNED TO FIELD FOR MAINTENANCE. THE AIRCRAFT LANDED WITHOUT INCIDENT AND TAXIIED TO GATE. MX REMOVED AND REPLACED THE NR 2 DISPLAY FAN, OPS CHECKED GOOD.