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When I installed Backtrack 5 R3, I chose to dual boot, it completely erased my BIOS and installed GNU Grub as the first thing that shows up when I boot up.

The "Press escape for startup options" output still shows, but if I press escape, it says "BIOS is missing or corrupted". I would like to boot the Windows installer from my USB stick (testing out Windows 10), remove GNU GRUB, and flash back my BIOS while still being able to dual boot Backtrack 5 R3.

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  • I think it's very unlikely that there's anything wrong with your BIOS. However, installing Grub certainly replaced your disk's old MBR and Windows gets confused by non-Windows MBRs. Unless you made a backup of the MBR the easiest way to get things back into a state that Windows can cope with is to run the Windows Fixmbr utility.
    – PM 2Ring
    Oct 25, 2014 at 13:58
  • Ok well how am I supposed to get into the recovery console then? I can't boot to anything other than the installed windows 7 or backtrack from Grub.
    – Spencer123
    Oct 25, 2014 at 22:34
  • If you don't have any Windows install or recovery disks, you can download an .iso for a recovery disk from Microsoft. See this answer
    – PM 2Ring
    Oct 26, 2014 at 4:01

2 Answers 2

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I found the answer over on SuperUser.

At the Grub menu press "C" to get to the Grub command line. Typing ls at the command prompt will list the devices grub has found.

grub> ls

Of course it may be difficult to determine which drive is the USB stick you want to boot. You can ls within the devices to try to figure that out.

grub> ls (hd0,1)/

Once you find the proper device, set it to root.

grub> set root=(hd0,1)

Or the older syntax:

grub> root=(hd0,1)

After setting root, enter these commands do boot using the bootloader on the device:

grub> chainloader +1
grub> boot

This should work with any bootable disk.

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  • This works if the disk's partition table is MBR, and so Windows boots in classic BIOS style. If a GPT partition table is used, Windows will be booting in UEFI style, and the chainloader command will be chainloader /efi/Microsoft/Boot/bootmgfw.efi instead. And yes, Windows couples the selection of system disk partitioning type and boot method together, so these two are the only supported combinations.
    – telcoM
    Mar 26 at 17:17
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Ok I finally figured it out. My BIOS actually was corrupted so I replaced the BIOS chip, booted to recovery console from recovery disk, and then fixed my MBR. I can finally boot into something other than Windows and Backtrack!

Not sure how to get into Backtrack now, since it just boots straight into Windows, but that's not important.

Thank you PM 2Ring for your help!

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  • Your motherboard manufacturer might have had a tool to flash the BIOS from Win7 instead of replacing the chip. Your fixed MBR probably overwrote Grub. Grub can probably be restored to boot into your Backtrack install using tools available after booting just about any Linux installer or "Live" disk.
    – robartsd
    Jul 30, 2019 at 15:40

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