Anne Arundel police said yesterday that James, a part-time employee at the electronics store, was vacuuming the floor in a back room shortly after 7:30 p.m. when sales manager Steve Monoiodis and Laurie Hendricks, another employee, heard a scream. They ran into the room and found the teen-ager holding the handle of the vacuum cleaner and leaning against a metal shelf in obvious pain, police said. Mr. Monoiodis told police he touched either James or the vacuum cleaner and was shocked slightly. Mr. Monoiodis unplugged the vacuum and the teen-ager fell to the floor, police said.