As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS NOT GROUNDED. EMERGENCY DECLARED. DURING DESCENT, RECEIVED *STABILIZER* EICAS MESSAGE AND HAD UNCOMMANDED STABILIZER MOTION. CMCF SHOWS MAINTENANCE MESSAGE 27-12822/27-12841. ACCOMPLISHED FIM TASK HORIZONTAL STABILIZER SYSTEM TEST IAW AMM B787-A-27-41-00-06A-300B-A WITH NO FAULTS FOUND. EICAS STATUS MESSAGE NO LONGER ACTIVE. CHECKED HORIZONTAL STABILIZER MOTOR FOR LOOSE CONNECTORS WITH NO DEFECTS NOTED.