As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN THE PILOT PUT THE LANDING GEAR HANDLE IN THE DOWN POSITION THE ACFT BATTERY FAILED, WHICH CAUSED THE ELECTRICAL SYSTEM TO DROP OFF LINE. PILOT COULD NOT DETERMINE IF THE LANDING GEAR WAS IN THE DOWN AND LOCKED POSITION AND COULD NOT COMMUNICATE WITH ANYONE FOR A VISUAL CONFORMATION OF THE LANDING GEAR BEING DOWN AND LOCKED. PILOT LANDED THE AIRCRAFT WITH LANDING GEAR RETRACTED.