As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT RETURNED FROM FLIGHT DUE TO DURING CLIMB, ALL EMER LIGHTS TURNED ON & BURNED ODOR WITH NO EVIDENCE OF SMOKE WAS DETECTED. PERFORMED REVISION DETECTING IN THE M1671 BATTERY PACK THE CB P18-3 B-10 POPPED. O THE BATTERY PACK NR M1671 WAS DEFERRED IAW MEL 33-15-2 CAT C. THE BATTERY PACK NR M1671 WAS REPLACED IAW AMM 33-51-06, TESTED CORRECT & THE REPORT WAS CLOSED.