As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING INITIAL ACFT POWER UP, THE CREW NOTICED SMOKE COMING FROM THE FWD AVIONICS EQUIP AREA & FURTHER INSPECTION CONFIRMED THAT THE SMOKE WAS COMING FROM THE AVIONICS BATTERY WHICH IS DISPLAYING BLACK MARKS & SIGNS OF OVERHEATING ON THE SIDE.