As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GNDED. EMER POWER SUPPLY UNIT 14WL, FAILED SYS TEST DURING THE OPERATIONAL TEST OF THE CABIN EMER LIGHTING SYS ON TASK CARD 26L00025012. REPLACED EMER POWER SUPPLY UNIT 14WL. INSTALLED A NEW BATTERY & ACCOMPLISHED A SATISFACTORY OPERATIONAL CHECK IAW AMM 33-51-38. SEE AALA 201604269005 FOR ADDITIONAL PART.