As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EMERGENCY LIGHT TEST FAILS TEST WITH MESSAGE 'EPSU BATTERY EMER R' AND 'EPSU BATTERY EMER L'. PERFORMED SELF TEST OF LEFT AND RIGHT OVERWING EPSU'S. EACH EPSU FAULTED BATTERY. REPLACED LEFT AND RIGHT OVERWING EPSU BATTERIES REF MM. ACCOMPLISHED SELF TEST OF EPSU'S-SELF TEST OKAY. AIRCRAFT EMERGENCY LIGHT TEST NOW TESTS OK.