What was found
(CAN) WHILE TAXIING OUT FOR TAKEOFF, RED MESSAGE `ESS POWER ONLY` CAME ON FOR 5-10 SECONDS. NOTICED #2 BATTERY HAD CYCLED OFF THEN ON BY ITSELF, THEN ALL CAS MESSAGE CLEARED. MAY 15/2019: REPLACED LEFT DCPC (SN 259) FOR FLICKERING PBA & RED ESSENTIAL POWER ONLY CAS. CUSTOMER ALSO REPLACED RIGHT DCPC (PN 970GC02Y06, SN 261) DURING SAME EVENT DUE TO IT HAVING SOME HISTORY ALSO. (TC# 20190516011)