As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FOUND EMERGENCY POWER SUPPLY UNIT (10WL) AND FLASHING FAULT LIGHT. EPSU BATTERY CAPACITY TEST SHOWS ESCAPE SLIDE LIGHT IAW TSM 25-62-00-00-810-811-A. REPLACED L1 DOOR SLIDE EMERGENCY POWER SUPPLY UNIT OPERATIONAL CKECK OK. AIRCRAFT WAS GROUNDED.