As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) CREW TURNED ON POWER TO CARRY OUT PREFLIGHT CHECKS, A STRONG BURNING ODOR WAS NOTICED COMING FROM THE MAIN CABIN. THE CREW TURNED OFF ALL POWER AND NOTIFIED MAINTENANCE. WHEN MAINTENANCE TURNED POWER ON TO TROUBLESHOOT THE PROBLEM IT WAS NOTED THAT 1 SECTION OF THE CABIN OVERHEAD LIGHTING WAS NOT WORKING. FURTHER INVESTIGATION FOUND THE DAMAGED POWER UNIT, WHICH WAS REPLACED AND LIGHTING FUNCTION WAS RESTORED. IT WAS ALSO NOTED THAT THE CIRCUIT BREAKER FOR THE LIGHTING SYSTEM DID NOT TRIP OFF.