Get back to older version

I have the same problem than this post

The problem is no resolved at all, i guess it’s because i have some custom javascript. I can’t disabled it because i can’t access to the forum. With the previous verison it’s works fine.

How can i go back to beta5 ?

I think @techapj made mention of appending ?preview-style=none to the url to prevent the custom styles from rendering. Give that a try.