As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED: MID RIGHT EMERGENCY POWER SUPPLY UNIT COMMUNICATION FAULT MESSAGE DISPLAYED ON FLIGHT ATTENDANTS PANEL DURING SYSTEM TEST. MAINTENANCE REPLACED MID RIGHT EMERGENCY POWER SUPPLY UNIT PER AMM 33-51-38 AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK.