As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN APU SHUTS DOWN A NEGATIVE LOAD DISPLAYED. NO, HAD TO RETURN TO GATE, CX'D AFTER HEA. RING SUSPECTED CONTACTOR WELDED, LATE ACFT. VERIFIED APU GEN CONTACTOR IS NOT WELDED. R & R DC POWER MONITOR IAW -8MM 24-31-05. OPS CHECK GOOD. OK FOR SERVICE.