Problems with dual boot on Windows 10

I reinstalled the October release of EndeavourOS on one of the two SSD on a Thinkpad, with Windows 10 on the other. The installation seemed to go fine, but now it boots directly into Windows with no option to boot into EndeavourOS. I saw the discussion in response to the recent question ’ [Clean install of theWindows 10 on the first HDD with dual boot system on the second drive (SSD)]’ and checked the wiki, but I am still not clear on the exact steps to follow in my case. Thanks for any help to fix this.

Hello @recif
Did you have it installed before? Does your Thinkpad have UEFI bios? If so make sure Secure Boot and Fast Boot are turned off in UEFI Bios and you can also check the boot order and make sure it is set to Endeavour Grub not Windows.

Here’s some good reading that might help solve the problem: https://endeavouros.com/docs/system-rescue/
Note: whether your systems work with UEFI or BIOS legacy mode is very important information.

And in addition to what @ricklinux already asked, for solving the mystery we need more and exact details.
So could you show the output of the following 4 terminal commands (you can start the terminal by booting with your USB installer stick):

    inxi -Fxxxc0
    efibootmgr  # or: sudo efibootmgr, if it shows nothing without sudo
    sudo fdisk -l
    lsblk -fm

and after the above outputs, could you please explain the partitions, if there are any out of the ordinary stuff there.

But before doing anything drastic, consider making good backups. And Windows recovery disk (or something similar) just in case.

I had to reinstall due to a problem when I activated the nvidia driver. I didn’t realize that Secure boot had been reset when I reinstalled Windows. I deactivated it and I can boot into either OS by rearranging the boot sequence. I will try to figure out how to restore the grub selection menu. Thanks for your help.

I think it is just using the Windows bootloader and it is not detecting EndeavourOS.

What I think you need to do is install EasyBCD and add EndevourOS.

I have done this and it works with Windows 7 and my PC uses Legacy BIOS (note I have done this with other GNU/Linux distros). But not too sure about Windows 10.

@recif
As @manuel say’s if you are able to boot into Endeavour then use efibootmgr and see if the grub bootloader is actually installed. You can use efibootmgr to change the boot order also so that it boots endeavourOS grub first then Windows if it is actually installed. If it’s not showing up you’ll have to use the wiki and arch-chroot using the live ISO and reinstall grub for UEFI setup.

It https://www.supergrubdisk.org/category/download/rescatuxdownloads/rescatux-beta/
still helped me in such cases.

I used efibootmgr to fix the problem and all the partitions show up. Thanks to all of you for your help.

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I just reinstalled a dual boot Windows 10 and rescatux helped again. This is a debian-based target tool that does not require any command line operations to restore the MBR. I can recommend it to everyone.