As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING TAXI, PARKING BRAKE EICAS MSG ILLUMINATED AND PARKING BRAKE ILLUMINATED AC RETURNED TO GATE (BTB) AND MTX GROUNDED AC . MTX PERFORMED OPS CHECK OF THE PARKING BRAKE SYSTEM ,UNABLE TO DUPLICATE .OPS CHECK GOOD IAW AMM 32-44-00. AND RETURNED AC TO SERVICE