As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PRIOR TO TAKEOFF, ATTEMPTED TO ARM AUTOBRAKE SYSTEM. WHEN THE MAX BUTTON WAS PUSHED, THE BRAKES LOCKED UP. ANTI-SKID SYSTEM OPERATED NORMALLY. DEFERRED PER MEL NR 32-42-07 DMI CONTROL NR 20126 TS PLAC INSTALLED, MXC NOTIFIED. DSMER 8973. DMI NR 20126 AUTO BRAKES WOULD NOT ARM. REMOVED AND REPLACED AUTO BRAKE CONTROL UNIT AND PERFORMED OPS TEST IAW 32-42-54. CKS NORMAL. DMI 20126 CLEARED. PLACARD REMOVED.