What happened to my machine is, not the pump or pipe but the lock at door has been touched. My wife cleaned the door and she accidentally touched the lock at the top of door. The machine stopped drain before rinse cycle.
I firstly followed everyone's idea to check the pipe and pump. But problem persisted. I started thinking about the real cause. The machine was working fine before she cleaned the door and panel. So she must touch something. The lock has an adjust nob to adjust the height of tongue sticking out to trigger the switch.
So I use a screwdriver to give it a small adjust based on the manual. The machine came back to normal. I figured this switch send signal to control board for rinsing or the board will check the switch before drain. if there is no signal or weak signal, draining will not start.