Had the same thing. I followed a Youtube video for getting error codes and got an E6 error code. Aqua Sensor. That is a little photovoltaic that senses how dirty the water is. $38 part but the replace video looked intimidating.

Since there was some greasy residue in the bottom I took a paper towel and wiped it out and then stuck the paper towel into the the two holes where water would drain and cleaned those tubes. Voila. It worked. I got it to do a whole cycle. Then I cleaned the whole thing with the vinegar and baking soda process from Wikihow. So just clean those tubes with a paper towel.

Wife says I saved us $1K because we didn't have to get a new dishwasher. I guess $300 and an argument. $300 for the service call and an argument over whether to spend $300 to fix a 12 year old dishwasher at it's "end of life." You have to take the whole dishwasher apart to get to the part and that was a bit beyond my "gumption." So it might have been even more than $300 in which case we're back to saving the $1K for a new one.