As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 2046 - DCA-BOS - EMERGENCY LIGHTS - EMERGENCY LIGHT TEST FAILED, FORWARD LEFT EMERGENCY POWER SUPPLY UNIT (EPSU). REMOVED AND REPLACED FORWARD LEFT EMERGENCY POWER SUPPLY UNIT AND BATTERY PER AMM 33-51-38. OPERATIONAL CHECK WAS GOOD.