As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
APU AUTO SHUTDOWN WITH FAULT LIGHT ILLUMINATED TWICE. RTB - BITE OF APU CONTROLLER SHOWS HIGH OIL TEMP LAST 2 S/D WITH NO MINI FLAGS. PULLED MCD FOUND METAL. PLUNGER STUCK ON APU AFTER CHIP REMOVAL. NO OIL IN APU. REPLACED APU PER AMM, OPS CHECKS GOOD.