As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: FAULT MESSAGE EPSU(11WL)EXT L/DEU-B(300RH6) DISPLAYED DURING THE EMERGENCY POWER SUPPLY UNIT SYSTEM TEST. .MAINTENANCE DISCOVERED BROKEN WIRE FOR CONNECTOR 261VC7 UNDER SEAT ROW 12AB, REPAIRED WIRE AND ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK PER AMM 33-51-01.