This is more of server configuration than wordpress itself. We simply won’t be able to fix this within wordpress. We need to work on the backend to resolve all those 404s. Hence, I asked you to check the .htaccess file to see if it has been modified since the browser is not able to access all those JS and CSS files that it needs to function properly.
The htaccess seems to be fine. Looks like it is some other server configuration. Probably file permissions or a htaccess files in subfolders blocking access to files. Any server admin should be able to get to the root of the issue. Let’s hope hosting does.