Maytag MDB5100AWB Dishwasher not draining

More than likely the filter is clogged,remove the spray arm(there is a threaded cap in the center of the arm twist it to the left,then remove the # 15 or 20 torx(star shaped) screws out of the filter cover(around the edges)The filter is round and runs around the outer edge of the pump housing it lifts right out,clean it and reverse the process.It's the most common issue with not draining on this model.

The drain hose needs to be higher at the point where it enters the sink cabinet than the drain connection to the sink drain. The drain line near the pump may have a back-flow prevention valve that is not working. I'm assuming that most of the water was pumped out initially.