As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING C1 HBBC REPLACEMENT, UNABLE TO DISCONNECT BATTERY WITHOUT EMER LTS IN POLARIS SECTION TURNING ON. FOUND WELS CU CLASS 17 INOP AND NO COMM. CONTROL UNIT REPLACEMENT NEEDED. REPLACED CLASS 17 EMERGENCY LIGHT CONTROL UNIT. CONFIG SHOWS 28 OF 28 RESPONDING. LOADED CONTROL UNIT SOFTWARE. EMERGENCY LIGHTS OPS CHECKED GOOD REF AMM DMC-B787-A-33-51-07-01B-720A-A.