As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
STRONG SMOKE SMELL FROM AFT RIGHT CABIN CEILING. REMOVED CEILING PANEL, OXY GEN PANELS AT 39, 40 AND 41HJ. REMOVED PSU AT 40HJ AND NO INDICATION OF OVERHEATING BUT STRONG SMOKE SMELL STILL PRESENT. FOUND APU BATTERY CAUSING SMELL. REPLACED APU BATTERY CHARGER AND APU BATTERY.