As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAXI OUT TO TAKEOFF, CREW HAD A BRAKE FAILURE. ACFT DEPARTED TAXI WAY & STOPPED WHEN THE RT GEAR SANK INTO THE DIRT. ACFT WAS RECOVERED & INSPECTED FOR DAMAGE. NO DAMAGED NOTED BUT DETERMINED THAT BRAKE CONTROL UNIT FAILED. INSTALLED REPAIRED BRAKE CONTROL UNIT & RETURNED THE ACFT TO SERVICE.