As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
BURNING SMELL ON THE FLIGHT DECK FIRST OFFICER SIDE. NOTICED NO MALODOROUS SCENTS IN ACFT FWD OR CABIN. RAN BOTH PAC 1 & 2 OFF OF APU AT FULL HOT & FULL COLD INDIVIDUALLY ON 4 MINS CYCLES. CHECKED ALL FLIGHT DECK LIGHTS & POWERED ON ALL AVIONICS, STILL NO ODORS ANYWHERE AT THIS TIME. PILOTS REPORTED SMELL ON INITIAL POWER UP OFF OF GPU WITH NO APU OR ENGS RUNNING.