TheMechanic,
FYI, I am having the same issue since I did the same WP update and theme updates.
I have tried the plugin folder rename hack without success.
The last successful log events for my website before it started reporting “500 Internal Error” were
/wp-admin/update.php action=update-selected-themes&themes=twentyfourteen%2Ctwentythirteen%2Ctwentytwelve&_wpnonce=c2ca591aaa 80 – {InfoRemoved} 200 0 0 6687
/wp-admin/load-scripts.php c=1&load%5B%5D=hoverIntent,common,underscore,backbone&ver=4.1 80 – {InfoRemoved} 200 0 0 187
/wp-admin/load-styles.php c=1&dir=ltr&load=dashicons,wp-admin,buttons&ver=4.1 80 – {InfoRemoved} 200 0 0 250