Indesit D41 – not doing much at all except beep

The dishwasher seems to have stopped doing much at all except beep at me.

The model is an Indesit Slimline D41UK Type Number LS 08-BIT100

When turned on to any setting it lights up the relevent green light and then does nothing at all – doesn’t drain the dirty water at the bottom, doesn’t pump new water in. When I turn the dial back to reset I get 4 beeps. and none of the green lights stays lit.

I’ve tried tipping the machine back and draining water out of it (maybe I didn’t do that well enough though), I’ve made sure that there’s water in the pipes and I don’t think that there’s anything blocking the filter of drain hose.

Anything else I can try before I either get something new or call in a repair man?

This forum and site gave me the confidence to change my washing machine drain pump myself, so I’m hoping you can help this time too.

PS – I ought to say that the door hasn’t felt as though it’s been latching recently, although this didn’t seem to stop the dishwasher working.