If you open the door and look inside the dishwasher is there any water in the bottom of it?
There was a little water in the bottom, but we managed to empty it out with a ladle and sponge.
Ok i think the humming you hear is the drain pump. As the first thing it does is brings the pump on. If this jams then it just sits there doing nothing but humming.
What you need to do is pull it out from under the unit and remove the right hand side panel. From there locate the drain pump and remove it and clear out any debris from there as sometimes glass or bits of food can jam the pump impeller up.
Once its clear refit the pump and retry it and see how it goes from there.
Hopefully it may be just a blocked pump and you wont need to get a new dishwasher.
So try that if you can and see what you find and let me know.