With dual boot I can no longer get into BIOS

[asaret]

I bought a HP-Compaq-8100-Elite-CMT; and it came with Windows 10. I added on Linux Mint as a Dual Boot. On Grub Linux and Windows appear as options. Only Linux will work. I read that if I went into BIOS and disabled Fast Boot, and Secure Boot, that Windows might start. However F12 no longer appears at the lower right hand corner; and as a check the HP description of this Desktop specifies that F12 is the BIOS key.
I tried shutting down the unit; and at restart either continue to press, or to hold the F12 key. I get the message:

Attempting Boot From IBa GE Slot 00CB v1353 (PnP Device)
Interl(R) Boot Agent GE v1.3.53
Intel(R) Boot Agent PXE Base Code (PXE-2.1 build 089)
Client MAC ADDR: 2C 27 D7 24 06 A0 GUID: 2DE89DBF 3699 E011 BBDA D72406A02
DHCP..../

Then it exits; without going into BIOS.
..........
I am getting no where with the F keys; or ESC.
A friend recommended:
To check out rEFInd and download the usb image.
https://www.rodsbooks.com/refind/getting.html
He said that this works and looks a lot nicer than grub for UEFI systems; and to make a bootable flash drive by following the instructions.
I went as far as I could.
In the rEFInd README I saw this:
"Be aware that the disk image file uses GPT, and the GPT data structures are sized for the disk image, which is very small by today's standards. Thus, the backup GPT data structures will be placed early on the disk. Most OSes
cope well with this, but you may want to correct the problem if you want to use the disk for other purposes in the future."

I will use a new USB for this.

rEFInd README recommended "dd if=refind-flashdrive-{version}.img of=/dev/sdx"

~$ lsblk
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sda 8:0 0 931.5G 0 disk
├─sda1 8:1 0 350M 0 part
├─sda2 8:2 0 97.7G 0 part
├─sda3 8:3 0 9.8G 0 part [SWAP]
└─sda4 8:4 0 823.8G 0 part /
sdb 8:16 1 58.9G 0 disk
└─sdb1 8:17 1 58.9G 0 part /media/edhe/USB DISK
sdc 8:32 1 15.5G 0 disk /media/edhe/6126-4BCD
edhe@HP-Compaq-8100-Elite-CMT:~$

With no mention of Windows??

/Downloads/refind-flashdrive-0.11.2
-rw-rw-r-- 1 edhe edhe 7.3M Oct 22 17:03 refind-flashdrive-0.11.2.img


Is this the right command:
sudo dd if=/home/edhe/Downloads/refind-flashdrive-0.11.2/refind-flashdrive-0.11.2.img of=/dev/sdb1

[pbear]

You can't use rEFInd on a BIOS machine. And although it apparently has been upgraded to Win10, a quick search shows yours originally shipped as Win7.

[Mute Ant]

"In GRUB both Linux and Windows appear as options. Only Linux will work." Strictly speaking, this is a Windows problem. If GRUB starts, and there's an option for Windows, and it doesn't work, you need a Windows Weeble, not a Linux Gnome.

At the Installing-Two-OS-On-The-Same-Drive level you should prepare for complete loss of the hard-drive contents. Like having all your personal files backed-up on something removable, a persistent bootable copy of the re-install media for each OS and knowing the License Key for your Windows.

"of=/dev/sdb1" This will write the .img file to the first partition of drive sdb and that's probably wrong. A booting image needs to go right at the start of a device, so the boot code can be read from the first sector of the drive. "of=/dev/sdb" is probably how it's meant to be written. Mint can do this for you, with the USB Image Writer accessory.

It's not likely that the contents of the hard drive are stopping you from accessing the BIOS screens. Some machines don't have a hard drive, they boot from code downloaded through the ethernet cable. That's what your F12 message is showing... "PXE" and "MAC ADDR" ...it is trying to boot from the network, not go into a BIOS screen

"Why doesn't F12 work?" would be a good place to start. "Why don't I try Delete instead" would be something to try. Or F8. Knowing which BIOS you have would reduce the number of choices.

Please don't be tempted to upgrade the machine's BIOS. That is something you do when the machine is working properly but there's a subtle, documented fault common to all machines, not just yours. It won't fix gross local errors like...
My-Technical-Advisor-Is-Incompetent
Problem-In-Chair-Not-In-Computer
Smarties-Stuck-Under-The-Delete-Key

[asaret]

Thank you both for your replies.

[rene]

On this here HP Compaq 8000 Elite the setup key if F10; F12 is network boot indeed.

On this here HP Compaq 8000 Elite you will however also not find anything concerning fast and/or secure boot; you'll likely need to look elsewhere for a fix.