Hi and thank you for using Just Answer
Ok if all it will do is pump out then the anti-flood switch in the base will be activated. Water will be in there causing this.
What you need to do is pull the dishwasher out and tip it 45 degrees backwards. This will allow the water to drain out from the base. Once the water is out the anti-flood switch will reset itself. Then retry the washer and see how it goes from there.
If it does it again then there will be a leak in there which you will need to find and fix to cure the problem here. I wish you the best.