Disconnect the battery and turn the crank clockwise by the bolt to be sure it is free.
If the starter engages at full amperage and nothing turns, the battery cable will get hot very fast. Turn the headlights on and try it. If the headlights dim out either your battery is dead or you have a bad connection at the positive post or a bad ground. If the lights stay bright either the starter is not engaging, the wire is bad down near the starter, or you have a bad ground strap.
Are you sure you hear the starter solenoid or just the starter relay in the plastic box in front of the battery?