Dishlex global 450 _ how do i fix fill level time fault? displaying oF?

Hi There, I have the above dishwasher and saw your advice on fixing fill levels - my display is showing the oF message and the pump to drain remains on whilst mains is connected. turning off mains does not clear message. holding eco button down does not clear message? is there anything else i should do in terms of removing parts to assist the process? I have cleaned out all of the drainage bowl and all is clear. i would prefer not to call a tech and am happy to pull most things to pieces my self if you have a little guidance. thanks