As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
COMPLIED WITH CABIN EMERGENCY LIGHT TEST, AFTER TEST WAS PERFORMED FAULT EPSU BATTERY EMER L WAS SHOWN ON CIDS PANEL. TESTED SYSTEM TWICE, FAULT SHOWED BOTH TIMES. REMOVED AND CLEANED FWD LEFT BATTERY CONTACTS AND REINSTALLED BATTERY IAW MM 33-51-38. OPS CHECKS GOOD REF MM33-51-00-710-001-A.