So it does the initial drain, but then doesn't fill with water, or very little?
Unplug, remove door outer panel and the lower cover plate. Look into the left lower corner under the cavity, you will see a corrugated translucent hose - this has a bad habit of filling up with grease and preventing the machine from filling. It's a push fit at both ends, so pull it out and clean thoroughly. If this still doesn't clear the problem, you may need to clear the pressure chamber. Lid and left hand side panel have to go, the pressure chamber is the unit with the wires and switches. Remove the large fill chamber, then the pressure chamber can be pulled out. If it looks like it has food detritus in it, boiling water is good (careful......), if it's really bad, it will all pull apart for a proper clean.