I found a softlock: If you get the sword, die because of the zombie (or an elevator) and respawn at the first checkpoint at the beginning because you didn't use the other checkpoints, you won't be able to get back where you were because this room (image 1) don't have the box used to go to the next room anymore (image 2)
![](https://img.itch.zone/aW1nLzg2ODIxMjgucG5n/original/gwwK0K.png)