As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IAH - FLIGHT 2339, DURING PRE-FLIGHT INSPECTION THE CREW REPORTED SMOKE TO BE COMING FROM THE OVERHEAD HYDRAULIC PANEL. MAINTENANCE REMOVED AND REPLACED THE HYDRAULIC CONTROL PANEL, OPERATIONALLY CHECKED WITH NO DEFECTS, AND THE AIRCRAFT WAS APPROVED FOR RETURN TO SERVICE.