What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
An interview with the pilot revealed that following an unsuccessful attempt at starting the aircraft engine, the aircraft experienced a dead battery. Unable to start the engine utilizing the battery, the pilot elected to hand start the aircraft. The pilot stated that prior to attempting the hand start, he positioned the engine controls for a flooded start (throttle 1/2 throttle and mixture control to the idle cut-off position), set the parking brake, and briefed one of his non-rated passengers to hold the brakes and advance the mixture once the engine started. The passenger stated that when the engine started, he pushed the mixture control in as he had been briefed however, the brakes did not hold and the aircraft began to move forward rotating to the left about the left main wheel. The pilot was unable to gain access to the cockpit to stop the aircraft which struck a hanger causing damage to the left wing and propeller.
As the FAA filed it
AN INTERVIEW WITH THE PILOT REVEALED THAT FOLLOWING AN UNSUCCESSFUL ATTEMPT AT STARTING THE AIRCRAFT ENGINE, THE AIRCRAFT EXPERIENCED A DEAD BATTERY. UNABLE TO START THE ENGINE UTILIZING THE BATTERY, THE PILOT ELECTED TO HAND START THE AIRCRAFT. THE PILOT STATED THAT PRIOR TO ATTEMPTING THE HAND START, HE POSITIONED THE ENGINE CONTROLS FOR A FLOODED START (THROTTLE 1/2 THROTTLE AND MIXTURE CONTROL TO THE IDLE CUT-OFF POSITION), SET THE PARKING BRAKE, AND BRIEFED ONE OF HIS NON-RATED PASSENGERS TO HOLD THE BRAKES AND ADVANCE THE MIXTURE ONCE THE ENGINE STARTED. THE PASSENGER STATED THAT WHEN THE ENGINE STARTED, HE PUSHED THE MIXTURE CONTROL IN AS HE HAD BEEN BRIEFED HOWEVER, THE BRAKES DID NOT HOLD AND THE AIRCRAFT BEGAN TO MOVE FORWARD ROTATING TO THE LEFT ABOUT THE LEFT MAIN WHEEL. THE PILOT WAS UNABLE TO GAIN ACCESS TO THE COCKPIT TO STOP THE AIRCRAFT WHICH STRUCK A HANGER CAUSING DAMAGE TO THE LEFT WING AND PROPELLER.