Fixing the Media – Add New button problem

Hi all. Just for the record, I fixed this common error by replacing all files & folders except the wp-content folder from a fresh download of WordPress. 3.5.1. No clue what the specific problem was.

This was the issue:
Media > Add New goes to blank white screen.

These steps did not work:
1. Deactivated all plugins
2. Switched theme from child to Twenty Eleven and Twenty Twelve
3. Renamed my plugins folder “plugins.hold” using ftp, logged out and back into the dashboard, noted the lack of plugins, renamed the folder back to “plugins”.
4. The “Jose Vega Fix” found at:
http://wordpress.org/support/topic/wordpress-35-add-new-media-not-working?replies=19