Grub is not installed during elementary OS installation. What to do?

Question

linux

Good day to all!
I decided to try installing elementary OS as a second system. At the end of the installation, it gives an error: "The command 'grub-install /dev/sda' failed. This is a fatal error . " When you start the computer without a disk, windows starts.
As I understand it, the operating system is being installed, because when you reload from the installation disk, it offers to install the OS next to elementary. I rummaged through the Internet, found the same problems, basically everyone throws off links to the manual on the ubuntu website for restoring Grub ( GRUB recovery ), installed elementary on the new one and immediately after the error started the console, first used the first recovery method, issued a warning:"Sector 32 is already in use by the program 'FlexNet'..." and Installation finished. No error reported . I decided to try the second method, so that "for sure" (Restoring using chroot) would give an error: "cannot find EFI directory" .
Maybe the problem is in this EFI / UEFI? I have a graphics BIOS on my motherboard...
After that, when you turn on the computer, a black screen starts up with the inscription grub> . In that manual there were also tips on how to restore grub from this mode, but they were also unsuccessful. As a result, I had to restore the Windows bootloader.
Please help a noob) How can I smoothly install elementaryOS as a second system and get this Grub installed correctly?) Thank you!

Answer 1

The problem was solved, magic in general :) After I restored the windows bootloader, the next day I decided to try again to install grub using the first method, at the end there was a warning again, but after rebooting, Grub opened with a choice of OS.
UPD : I installed another elementary OS image, an older version, found it on my computer by accident, got up fine with grub. So if someone has such a problem, then either use the GRUB recovery instruction or install a different OS image.

Answer 2

It was fine for me if I started the installation after establishing an Internet connection. And in order for grub to work properly after installation, the system set Boot-Repair

sudo add-apt-repository ppa:yannubuntu/boot-repair
sudo apt-get update
sudo apt-get install -y boot-repair && (boot-repair &)