As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: A FAINT TRIPLE-BEEPING NOISE IS REGULARLY HEARD IN THE CABIN NEAR AND AFT OF THE OVERWING EXITS. MAINTENANCE FOUND BATTERY AT EMERGENCY POWER SUPPLY UNIT 12WL FAULTING. EMERGENCY POWER SUPPLY UNIT 12WL (AALA202501249077) AND THE BATTERY (AALA202501240058) PER AMM 33-51-38. A SATISFACTORY OPERATIONAL CHECK WAS ACCOMPLISHED WITH NO ISSUES OR NOISES NOTED.