WF9E starts beeping 35 minutes into cycle

Hi, our dishwasher suddenly stopped working. On the Eco wash, 4 hour cycle it stops after 35 minutes and in quick wash after about 8 minutes.

Dishwasher is still under warranty.

What happens is that it starts beeping 10 times then quiet and then again 10 beeps. There are 4 orange lights on the dashboard. The dishwasher is draining but I have noticed that it still continues draining even when I open the door. It used to switch off whatever it was doing in the past?

I have disconnected the drain pipe and the in flow pipe to check but there is no obstruction.

We clean dishwasher once a month and empty rinse filters before every use.

Any suggestions what it could be? Engineer not coming for 3 weeks.