From: http://www.windowscentral.com/errors-windows-10-upgrade-fix

Fixing message 80240020 ….

Also: http://www.digitaltrends.com/computing/common-problems-with-installing-windows-10-and-how-to-fix-them/

Also: http://windows.microsoft.com/en-us/windows-10/upgrade-install-errors-windows-10

Also: https://www.microsoft.com/en-us/software-download/windows10

Manual Download

Also: http://www.infoworld.com/article/2989972/microsoft-windows/windows-10-installation-problems-and-what-to-do-about-them.html

From: http://download.wsusoffline.net/

Using "WSUS Offline Update", you can update any computer running Microsoft Windows and 
Office safely, quickly and without an Internet connection.