As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELECTRICAL BURNING SMELL NOTICED WHEN PULLING INTO GATE WHILE BRINGING APU ONLINE. <[01] FOR 10 MINUTES? PERFORMED ENGINE RUN ON BOTH ENGINES; PUT A LOAD ON APU; ENGINE; OPERATED HYDRAULICS; AND DIFFERENT BLEED SOURCES TO DUPLICATE ISSUE AND ISSUE COULD NOT BE DUPLICATED. ALSO; CYCLE APU GENS AND ENGINE GENS TO TRIGGER ISSUE AND ISSUE CANNOT BE DUPLICATED REFERENCE AMM 71-00-00; OPS CHECK GOOD NO STRANGE SMELL DETECTED.