As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
EICAS MSG(L, R)UTIL BUS OFF DISPLAYED. UTILITY BUS OFF LIGHT ILLUMINATED SYS FAILED TO RESET. THIS OCCURRED DURING (GRD OPRN, 2 GEN OPRN INFLT). (01=L,02=R,03=L&R) 3 BITE OF BPCU SHOWED (REPLACE BPCU) AND SERIAL DATA LINK FAILED. REPLACED BPCU. RAN BOTH ENGINES AND DURING ENG START UTILITY BUSES DROPPED OF LINE UNTIL ENGINES WERE RUNNING WHICH IS NORMAL OPERATION. SYS OPS CKD NORMAL. NO FAULTS FOUND ON BPCU.