I think we should do a clean install of Windows 8. Download a copy
here. After you made the flash drive or DVD, and before you start the clean install, I think you should try the Windows Image Backup again using the Windows 8 media. It might make a difference. Here are instructions on how to boot into Advanced Options with the Windows 8 install media. You can skip down to Method 4.
How To Access Advanced Startup Options in Windows 10 or 8
If it doesn't work, then follow my instructions in the post above, #76, to start the clean install.
Before you start the clean install, go to your manufacturers website and download the drivers for your wireless card, LAN, (this is what a network cable plugs into), and graphics. Windows might not come with them pre installed. Do you know how to install drivers? Do you have access to another computer if you can not get back on the Internet?
After the clean install and before you install any drivers or programs, try the System Image Backup again with the Windows 8 install media.
If everything fails, and you can not get back on the Internet, just install Windows 10 again.