Buttons not showing and text showing in white color in Editor

Hi,

I am not able to see any buttons in my page editor.
Moreover, the text inside the editor is loading in white color, so its not visible.

I have seen similar issues listed before and tried everything listed but to no avail. Here is what I have done already:
1. Tried accessing my dashboard on different browser
2. Tried accessing my dashboard from different system
3. Clear browser cache
4. Installing Google editor plugin
5. Installing Advance Tiny MCE editor plugin
6. Manually updating css and js files
7. Updating wp-config file to add define(‘CONCATENATE_SCRIPTS’, false);
8. Downgrading to a previous version of WordPress
9. Disabling all plugins

Nothing seems to be working. I am stuck on this issue for more than a day. Can someone please let me know if there is a known solution ?

Thanks,
Mayank