magefix

You don’t affect wp-content – plugins & themes, you can safely upload the entire wordpress archive content.

Updating_WordPress – “NOTE – you should replace all the old WordPress files with the new ones in the wp-includes and wp-admin directories and sub-directories, and in the root directory (such as index.php, wp-login.php and so on). Don’t worry – your wp-config.php will be safe.”

I got a simmilar error for one of my clients, days ago. I simply uploaded again all the core files wordpress uses , you simply download wordpress-4.5.3.zip ; let me know how it worked.

You’re getting now: “ERROR: Cookies are blocked due to unexpected output.”

discovered one plugin causes errors when I disable it and the login box appears but still cannot login.

Why you can’t login? Which is the error?

After loggin in into your Cpanel, do you have a “Quickinstall” button, right under Phpmyadmin? If yes, you can try that.
More info: https://youtu.be/wLzaU2gq9Xs?t=479

Here is a tutorial which might help:[link moderated – keep support on this site Forum Rules.

If you still get the redirect you might try setting the debbug on, to see if some errors show up.
edit wp-config.php
look for:
define( ‘WP_DEBUG’, false );
change to:
define( ‘WP_DEBUG’, true );