If you need to update Concrete5 5.7 manually, follow this steps:

1. Download Concrete5 5.7 latest version
2. Extract the archive. The extracted folder will be named concrete5x.x.x (x.x.x being the version number for instance concrete5.7.2.1)
3. In the folder delete everything EXCEPT:
• The "concrete" folder
• The "index.php" file
4. Put the folder inside your site's root "updates" folder so now you have root/updates/concrete5.x.x.x and inside it only a folder "concrete" and a file "index.php"

When that's done:

1. Open your browser and navigate to your site
2. Logged in as an administrator go to your System & Settings page
3. Under Backup & Restore go to "Update concrete5"
4. There you should see a notice about an update available
5. Click on the "update" button at the bottom of the page

You should be all set