What was found
WHILE PERFORMING EMERGENCY BATTERY PACK CAPACITY PACK CHECK BEFORE 15 MIN MARK, FOUND MID AND AFT MAIN CABIN WALKWAY OVERHEAD EXIT SIGNS OFF, LH/RH AREA LIGHTS FROM ROW 16 AFT, LH/RH OVERWING DOOR EMERGENCY EXIT LIGHTS OFF, AND BOTH L2 AND R2 PAX DOORS EMERGENCY EXIT LIGHTS OFF. GROUNDED - YES. REMOVED AND REPLACED POWER SUPPLY BATTERY PACKS AT R/H AND L/H OVERWING ESCAPE HATCH, AND R/H AND L/H AFT PASSENGER DOORS REF B737-800 AMM 33-51-06-960-805.