As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT IN BASE MX. DURING ACCOMPLISHMENT OF CARD 26C22033001, EMER LIGHTING SYS DOOR SWITCHES OPERATIONAL TEST, FOUND AFT LT EMER POWER SUPPLY UNIT FAULT LIGHT ILLUMINATED. REPLACED EMER POWER SUPPLY UNIT & ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK IAW AMM 33-51-38-400.