Neff dishwasher continually draining after end of cycle?

My neff dishwasher, which is only just over a year old is not functioning as it should.

When a wash finished last night, I noticed some excess water in the bottom of it. I put it on a rinse, once I had emptied it, to see if it would drain away. The rinse ended and the dishwasher beeped to signify the end of the cycle, but when I opened it the dishwasher was making gurgling sounds. It seems to be draining continually, even when the door is opened.

I have tried resetting it, using the instructions in the manual, I have also tried putting a bit of water on the bottom of the dishwasher (this fixed it once before) but this just drains away and the noise continues. I have checked all the visible places that could be blocked, but I am not confident enough to take it apart.

Any advice would be appreciated.

Thanks