As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE VISIT: MAINTENANCE REPORTS DURING OPERATIONAL TEST OF EMERGENCY LIGHT SYSTEM MCDU SHOWS EPSU 3L (15WL) / DEU B (300RH5) IN PASSENGER CABIN. REPLACED EPSU 3L(15WL) IN PASSENGER CABIN IAW AMM 33-51-38-400-801-A AND PERFORMED OPERATIONAL TEST IAW AMM 33-51-00-710-801-A. TEST IS OK.