Had a sink blockage – fat. First tried chemical clearer no good but water and chemical flowed back into dishwasher cos waste pipe enters sink waste above the ubend where blockage was. Switched on dishwashe on prerinse after clearing blockage by hand. It emptied perfectly then just sat there with the 19 min timer on not going into cycle. Have reset and tried all programes but it will not begin to fill. Have checked filter in cold supply and no problem. Anyone help please? Grim