How can I fix my AEG Favorit 545i dishwasher?

We had a mains water leak near the boundary of our property recently. I attempted to run the dishwasher but obviously it requires mains water and so did not work.
The leak has now been repaired but, when I turn on the dishwasher, the drain pump runs continuously. Looking at the manual, I guess that the anti-flood device has been activated.
Is there any way we can reset this ourselves? We are competent DIYers.
My second question is to do with the age of the machine - it was new when we moved into this house 19 years ago and has always worked perfectly until now. Is it worth fixing?
Looking forward to your reply.