Do you mean the walls left and right or up and down?
If it's the walls left and right: Just go up!
If it's the walls up and down: On what system do you play? (Web, Windows, Mac, Linux)
I've tried the game on web and there don't seem to be any problems for me?
Here's a video of what should happen.
I'm very sorry to say, but I have no idea how to help you... There are some Let's Plays of the game on YT, if you're still interested in knowing the ending TvT