Ok which 3 lights come on?
the ones that you set the progam to wash with
I need to now which program lights are lit as that's an error code.
Number the 5 program lights from left to right with 1 on the left and let me know.
the last 3 from the left next to progamme button
Ok that's great thanks.
Them 3 lights flashing is a draining error code.
As you say you hear a buzzing noise this will be the drain pump. Its either blocked or faulty that's why its not draining the water out and giving the error code by the lights.
What you need to do is pull the dishwasher out from the unit.
Then you need to scoop out all the water inside the dishwasher.
Then you need to remove the side panels and from there locate the drain pump. It will have the grey drain hose going to it.
Remove the drain pump and check to see if theres anything stuck in there. Becarfull as its usually glass that's stuck in there.
Check the pump impeller that it turns ok it should ping round in stages. If its stiff to turn then it will need to be replaced.
So check that out and see what you find if you can and fingers crossed its just a blocked pump. If you need anymore info just get back to me.