When this happens with the pump running all the time its the antflood switch in the base is activated. The antiflood switch is the grey round thing clipped into the base which you will have seen when you replaced the drain hose.
What you need to do is tip the dishwasher 45 degs backwards to clear any water in the base as this will activate it. Then see how it goes.
But if theres no water in there then you need to remove the base again and check that flood switch is clipped into the base probberly as If it isn't the ploystrine in there can keep the micro switch activated.
Check them out first and see what you find and let me know.
I thought it might be something like that. There isn't any water in there so perhaps the thing isn't clipped together properly. Is there any way I can disable it?
You cannot display it as then it wont make the circuit it needs to be able to start.
But just check it and make sure its clipped in correctly and disconnect the wiring block and see if it has burnt out. As these switches can burn on the wiring.
Let me know how it goes.
I think that it's burned out. I took photos, attached, but there's a lot of burning around the contacts. Is it easy to order a new part?
Ok that's the cause of this fault so you need to replace the micro switch. To fit it you just need to open the casing the switch is in and swap the switch over from there.
But you will also need to retag the wiring. Don't refit the same block back otherwise it it will do the same again very quickly.
Click here for the switch