It seems that the recent WordPress 4.4 update got error when you update your script automatically.
When the WordPress updated, you will get blank page, and get the message:
SERVER ERROR 500
And it is simple to fix this problem,
just open your site with another browser, then you will get the following page:
Database Update Required
WordPress has been updated! Before we send you on your way, we have to update your database to the newest version.
The database update process may take a little while, so please be patient.
Just click the button and your site will be back!
Your WordPress database has been successfully updated!