broken dishwasher

[Account Closed]

I checked the dishwasher and ended with water all over the floor. The washer had finished, but water was still going into it, and the bottom, being full, excess water was coming out the still closed and locked door.

I turned the faucet off under the sink.

Now what? The washer is 15 years old. What happened? How did the water not get stopped, how did the drain not continue draining?
Do I call a plumber to install a new part, or buy a new washer?

ofgift