My Nissan Altima won't start

My 2009 Altima won't start. It has an electric key. When I push the brake and press the ignition button, the car just makes a clicking sound(doesn't even try to rev the engine). The battery is not dead because I can still turn on the radio.

Also, the brake is extremely stiff for some reason and it resists letting me push it down, which I need to do to start the engine.

Does anybody know what may be the problem? Spark plug, transmission, or some electrical problem maybe?