As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED A LOUD SQUEAL AFTER TAKEOFF. CREW ELECTED TO RETURN TO CLT AND LANDED WITHOUT INCIDENT. MAINTENANCE INSPECTED AND FOUND THE EXTERNAL GROUND POWER DOOR OPEN. MAINTENANCE SECURED DOOR CLOSED AND FOUND NO DEFECTS OR DAMAGE. AIRCRAFT WAS RELEASED FOR SERVICE.