As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 822 - CLT-BOS - EMERGENCY LIGHTS - EMERGENCY LIGHT TEST SHOWS "INT LOAD AFT L" FAULT. TEST OF POWER SUPPLY SHOWS INTERIOR LIGHT FAULT, BUT ALL LIGHTS ILLUMINATE WHEN TURNED ON. REMOVED AND REPLACED EMERGENCY POWER SUPPLY UNIT (EPSU) PER MAINTENANCE MANUAL 33-51-38.