As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CABIN EMERG LIGHT TEST MESSAGE, EPSU BATTERY EMER RT, DISPLAYED ON CIDS SCREEN. PERFORMED BATTERY TEST AT BATTERY REF MM 33-51-00. CONFIRMED BATTERY FAULT. REMOVED EPSU BATTERY AT RT EMERGENCY EXIT ROW REF MM 33-51-38. NEW BATTERY ORDERED, COMING FROM ORD TERMINAL. PERFORMED ELOTO REPLACED BATTERY IAW MM 33-51-38. OPS CHECK GOOD. OKAY TO CONTINUE.