On July 18, 1999, at 1400 central daylight time, an Engineering & Research 415-CD, N3895H, collided with a hangar when it inadvertently started as the pilot was pulling the propeller through, at the Wahoo Municipal Airport, Wahoo, Nebraska. The pilot was not injured. The airplane was substantially damaged. Visual meteorological conditions existed at the time of the accident. The flight was to have originated shortly after the accident. The pilot stated he was picking up his airplane after having had maintenance performed on it two months prior to this accident. He reported when he attempted to start the airplane, the battery only had enough power to rotate the propeller through one rotation. He reported he exited the airplane and was going to turn the propeller to "...get the engine at the top of its compression stroke." He reported he had done this in the past and upon using the starter again, "...the prop would have enough momentum to swing into a second rotation which was usually enough to start the engine." The pilot reported he turned off the master switch, but failed to turn off the ignition switch prior to moving the propeller. He reported he moved the propeller one- half of a turn and the engine started. The airplane traveled down a taxiway where it contacted a hangar. He reported that the impact left the airplane imbedded in the hangar door up to the wing spar. The pilot reported the accident could have been prevented had he "...[been] absolutely sure all switches [were in] the 'off' position prior to any attempt to hand-turn the prop. Better still, don't attempt to hand turn the prop without someone at the controls."