As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OUT, LT & RT UTILITY BUSS OFF CAUTION MESSAGES ON EICAS. NO LUCK RESETTING OR RECYCLING CIRCUIT BREAKERS. RETURNED TO DEPARTURE. PASSENGERS REPORTED A BURNING ODOR IN THE MID CABIN. FOUND BPCU WILL NOT POWER UP AND TO HAVE A FAINT ODOR. R & R THE BPCU, CHECKED OK.