motor hums, light works, fan won't turn
Could be a mechanical problem.  Try this: with the power OFF, try to rotate the fan with your finger. It should spin freely for awhile after you poke it.  If not, then something is mechanically impeding the travel of the fan blades.  

Check for anything touching any part of that rotating fan assembly.  Maybe some left-over protective packaging that you missed?  Or a wire that is bent in and pushing on the blades?

If not the above then good chance this is just a defective fan motor.