N,
I suggest that you remove the pump lid and inspect the O-Ring to make sure it is lubricated and looks undamaged.
Then add water to the pump. Keep in mind that it will start flowing back into the pool one the water gets up to the input pipe.
Also make sure that the floating weir door between the mouth of the skimmer and the skimmer basket is not stuck in the up position.
Put the lid back on and try the pump again.
Please let us know what happens,
Thanks,
Jim R.