What actually happens when you start it?
Is the drain pump running?
If so is it running all the time?
yes it is running all the time -makes the noise
When this usually happens its a water leak in the base of the dishwasher.
What you need to do is pull the dishwasher out and tip it 45 degs backwards. This will allow the water to drain out from the bottom so you may need a towel for this part.
Once the water is out the antiflood switch in the base will reset itself then the dishwasher should start again from there.
Then just monitor it and see how it goes. If it does it then theres a leak in there which you will need to find and fix to cure it.
Let me know how it goes.