As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) GPU VOLTAGE SPIKED WHILE PROVIDING POWER FOR ENGINE START. GROUND POWER WAS SHUT OFF AND ENGINES STARTED USING INTERNAL BATTERIES. BOTH ESSENTIAL DC ELECTRICAL CBS FOUND TRIPPED WHILE PERFORMING TAXI CHECK LIST. RETURNED TO GATE.