As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LOUD HUMMING SOUND HEARD 5 TIMES FROM FORWARD INSTRUMENT PANEL, FIRST TWO TIMES WITH STRONG ODOR OF HOT ELECTRONICS. CLEARED CLOGGED AIR INTAKES ON NR 1 AND NR 2 INS CDU'S. INSPECTED FORWARD INSTRUMENTAL PANEL AREA. PERFORMED EQUIPMENT COOLING TEST. ALL CHECKS GOOD.