How did the terrible grandmother stay in the void for a minute?

1, first open the door of a steam room in the underground garage, throw something into it, and then hide. The scary grandmother will hurry down and enter the steam room for inspection. After entering the steam room, the scary grandma will quickly come out and close the door, then put down the board and open it to lock the scary grandma.

2. At the resurrection point, I tricked the scary grandmother into coming in, then let the scary grandmother come to the bed, and then kept coming in and out, and the scary grandmother was stuck.