As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER ENGINE START STBY POWER OFF LIGHT ILLUMINATED WITH ASSOCIATED EICAS MSG. STBY BUS OFF. T/E PER WDM 24-33-11 FOUND DC STBY C/B ON P-6-1 PANEL POS A2 INOP. NO CONTINUITY WITH C/B IN CLOSED POSITION. REMOVED AND REPLACED DC STBY C/B, OPS OK PER M/M.