If your electromagnet does not work, it may be shorted. Sometimes re-winding the electromagnet may solve this problem. This usually occurs with 2 magnet rotors. The rotor will not start spinning on its own. Give it a slight push.
Rotor is jammed.
Find the exact cause and fix the problem. Moving the books may solve the problem. Electromagnet attracts the magnets instead of repelling them. Switch the battery connection wires. Bad connection in wiring.