Disaster Recovery Backup for a Windows 10 Fujitsu Lifebook T939

I got a new Windows 10 laptop. So what happens if the disc crashes? It did not even come with a DVD to install even the operating system (i.e. Windows 10 itself). Therefore I made a recovery image on a USB hard drive and a emergency boot USB stick to install that image when the disk is damaged. My approach below requires an external USB hard disk (or at least a disk physically different from your system disk) and a USB stick whose data can be and will be erased. According to Windows the USB stick had to have at least 16 GB of memory. But I used a 64 GB stick and it used most of it. From the size, compared to that of the disk image on the USB hard disk, it appears to me that Windows will also put a complete system disk image on the USB stick if it has enough space for that.

• Fully set up Windows 10 first.
• Next get your UEFI Bitlocker key. Login to your Microsoft account at
  https://account.microsoft.com/devices/recoverykey
  to get it. About 100 digits separated by occasional hyphens. Avoid typos in copying it to a safe place. (Not to your new computer).
• If you are happy with Windows 10, skip this step. But if you want to install Linux alongside Windows on your system disk, you need to create space for it. Use Cortana to find "Disk Management". Then shrink the big C: partition. Leave enough space for Windows to put additional files and applications, of course. Compare how much space is already actually used for Windows with how much you have available. If Windows does not want to shrink the C: partition enough even though there is plenty of free space, some files are in unfortunate places on the system disk. Then you will need to find a better partition manager. But on my new system there was no problem with files in unfortunate places.
• Get and install the latest Windows updates.
• Use Cortana to find "Control Panel", then select "System and Security", "Backup and Restore (Windows 7)". If you do not really use Windows 10 except in an emergency like me, select "Create a System Image". Otherwise, select "Setup Backup" (to the far right), which will include creating a system image too. Either way, this needs an external USB hard disk (not USB stick). The created disk image was a folder called WindowsImageBackup.
• To use it to restore a damaged system disk, however, you need a system repair DVD or USB stick. Since I did not have a DVD drive on my laptop, I used a USB stick. The link to create a system repair disk in "Backup and Restore (Windows 7)" only wants to do a DVD. So to use a USB stick what you need to do instead is hold the "Windows" key down and hit the "r" key. Then type in "RecoveryDrive.exe" without the quotes and create the USB stick. As noted, my USB stick was 64 GB.
• Restart the computer and check that you can still boot into Windows 10.
• Check that you can boot from the USB stick. First check the documentation for your computer for which key produces the boot menu. In my case that was F12. Then turn off the computer. Put the USB stick in the computer and turn it on. When the manufacturer name is visible, hit F12 or whatever. Select the USB stick to boot from. (Alternatively and more advanced, check the documentation for your computer for which key produces the BIOS settings. In my case that was F2. Then turn off the computer. Put the USB stick in the computer and turn it on. When the manufacturer name is visible, hit F2 or whatever, check that the USB stick is enabled as a boot option, and change the boot order so that the USB stick is first, then save and exit to boot into the USB stick. That is what I did.)
• You should now get a language and keyboard prompt, followed by various recovery options and a power off button. This indicates that the computer boots OK from the stick. Use the power off button, remove the USB stick, and restart the computer normally.