Wait for the current cycle to end and unplug the power cord once the appliance is idle. Carefully move the washing machine forward to reveal the water inlet and drain hoses.
Place a towel under the drainpipe connection and pull the hose out of the back of the washer. A small amount of water might come out onto the towel as you break the connection.
Clean around the opening where the drain hose was attached with a damp cloth to remove any hair, dirt or debris trapped in the opening. Lift the other end of the hose out of the standpipe, cutting the zip tie with scissors if necessary.
Place the blocked drain hose in a sink and flush it out with water from the tap. Massage the pipe with the water flowing to disloge any blockages. Use a long pipe cleaner or an unfolded metal coat hanger to probe inside the hose and clear stubborn material.
Rinse the hose thoroughly once the blockage has washed out and push the appliance end tightly back into the socket. Position the standpipe end back in place and secure it with a zip tie. Slide the appliance back into place, reconnect the power and try the washer again.