If the install is not completed then you would not choose an OS to boot as the restarts are automated through those screens until you set up your User account and initial settings.
But often the problem is that a driver
is hanging the install, so by entering the Device Manager during install you can uninstall any device in error (usually Display) to complete the install and update the driver for that device from desktop. Device Manager - Access During Windows 7 Installation
I'll need results of each step I give you starting with the earlier ones to know what to suggest next.