Can't enter BIOS setup on M4700 after enabling Secure Boot

Update:  I still get nothing on the laptop screen (ever), but on the monitor connected to the dock, once I wait for Linux to boot, Linux does come up.  I just don't see the bios messages anymore on the laptop screen or on the monitor connected to the dock.  Any ideas on how to get back to the bios messages?

Hi

I have used modeset in days of yore.

What if you change back from secure boot?

Is the Storage device UEFI?

Troubleshoot your Linux boot screen issue with Secure Boot enabled. Common causes include graphics driver conflicts, unsigned bootloaders, or BIOS misconfigurations, especially on Dell hardware with Linux Mint or Debian.

Quick Fixes First

Temporarily disable Secure Boot in BIOS to confirm it's the cause—enter BIOS (F2 on Dell), set Secure Boot to Disabled, ensure UEFI mode (not Legacy/CSM), save and exit. If the screen appears, the issue is Secure Boot compatibility.

If no display even after, reset CMOS: power off, unplug, remove motherboard battery for 5-10 minutes (or hold power button 30-60s), reinstall, then re-enter BIOS to verify settings.

Edit GRUB Parameters

Boot into GRUB (hold Shift or Esc during startup). Highlight the entry, press 'e', find the "linux" line ending in "quiet splash", add "nomodeset" at the end (e.g., quiet splash nomodeset), then press Ctrl+X or F10 to boot. This disables advanced graphics modes often conflicting with Secure Boot. Make permanent post-boot: sudo nano /etc/default/grub, add to GRUB_CMDLINE_LINUX_DEFAULT, then sudo update-grub && reboot.

Enable Secure Boot Properly

Linux Mint/Debian support Secure Boot via signed shim bootloader. Boot a live USB (disable Secure Boot first), chroot into your install, install shim-signed (sudo apt install shim-signed mokutil), regenerate GRUB (sudo grub-install --target=x86_64-efi --efi-directory=/boot/efi), then reboot and enroll MOK key if prompted (use mokutil). Re-enable Secure Boot in BIOS afterward. For NVIDIA GPUs, sign proprietary drivers separately.

Hardware Checks

Test with integrated graphics (iGPU) if available: remove discrete GPU, connect display to motherboard port, boot, then reinsert after fixing. Update BIOS from Dell support site via F12 boot menu on a FAT32 USB. Ensure GPT partition (not MBR) via live USB's disk management.

@anne_droid​ Thanks for the reply.  The whole problem is that I can't get to the BIOS to disable it.  There is no video output to either the laptop screen or the screen connected to the laptop's dock.  I did try removing the laptop and the CMOS battery, but did not wait for 10 minutes.  I probably waited for 2 minutes.

I don't think the problem is on the GRUB or Linux side as the issue occurs before it should access the disk to read the boot info.  Additionally, it boots Linux just fine.  I'm using Ubuntu, which is based off Debian, and I know it supports a signed bootloader, but not sure if that is the default when you build the bootable thumb drive to load Linux onto the computer.  I guess I'll have to see if I can find that info.  I like the idea of updating the BIOS from Dell support, except that once again I can't get to the BIOS boot menu via the F12.

I'll see if any of your suggestions help.  Thanks again for the ideas.

Regards,

SRG

There is a old Nvidia issue (on early UEFI-class computers) of getting BIOS-screens to appear via Display-Port (but HDMI works fine). First video appears at Windows (or Linux) login screen. It's usually on desktops, but makes sense that laptops are NOT immune.

Also, try without the Dock.

@Tesla1856​ Thanks for the reply.  The issue is with and without the dock.  Also, without the dock, it is just a laptop, so no HDMI port for me to use. There is only a display port built into the laptop, and the same for the dock.  The onboard screen is also dead until Linux actually boots.  Then I get the normal login screen.

Regards,

SRG

Sounds alot like this issue:

https://www.google.com/search?q=bios+over+display+port+nvidia+laptop

Does it have an Nvidia card? Can you force it to the Intel one?

I ran into it with a desktop and Nvidia GTX-1070. Coincidentally, I know that the problem also appears with Grub/Ubuntu until patched (Grub not immune).

Hi

Well if it boots Linux 'fine' and you do a restart .......

Then GrUB lists the BIOS as an option, without going via F12 hopefully.

Hi

Hope this helps...

Further research offers ...............

Your system must run GRUB 2.14+, UEFI mode, and firmware that supports the feature—check with fwsetup --is-supported in GRUB's command line.

It's distinct from systemctl reboot --firmware-setup (systemd-based), but both aim for the same UEFI access without key mashing at boot.

NOTA BENE.........

The command sudo systemctl reboot --firmware-setup instructs a systemd-based Linux system to gracefully shut down and then reboot directly into the UEFI/BIOS firmware setup interface.

Instead of restarting the operating system normally or requiring the user to rapidly press a specific key (like F2 or Del) during the boot process, this command sets an EFI variable that tells the firmware to automatically launch the configuration menu on the next boot. This is particularly useful for systems with very fast boot times or for remote server administration where physical keyboard access is not available. 

On Dell hardware, like you're familiar with, it works reliably in UEFI setups like Ubuntu or Arch.

Works very nicely for me.

@anne_droid​ Unfortunately, it's a Catch-22.  Since I can't see the output until the system hits a higher run-level, the GRUB menu's are not visible to me.  I can look at the GRUB config files once it's in multiuser mode though, but I'm not sure what I'm looking for.  I see the following section in it:

From a running Linux session try ............

sudo systemctl reboot --firmware-setup

WHEN/IF I edit GrUB, I tend to use the .......

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
GRUB_GFXMODE=800x600

Most modern systems (Dell included) seem to still, thankfully, use the VESA system.

This makes the words BIGGER,

and GrUB starts in 800x600, linux starts to boot in the same mode, then the graphics kick inand I get the resolution as per the settings.

@anne_droid​ when I restart using the systemctl command it appears to restart into GRUB, but I have the black screen still.  Are you saying that I should blindly type that command to switch the graphics?   Then try to reboot with the power button (because I can't see to do a graceful save and exit from GRUB).  

also, even if this works I suspect that it will enable me to see the boot messages for Linux as it's coming up, but not the bios messages to where I can manage the laptop bios settings menu.  

I  think getting back to the bios menu would be the key.  I could either revert back to the Legacy boot from the current Secure UEFI boot, or I could see if there's an option using the on chip Intel graphics instead of the Invidia add-on graphics.  

Regards,

srg 

@qsg001​ ,

I  think getting back to the bios menu would be the key.  I could either revert back to the Legacy boot from the current Secure UEFI boot, or I could see if there's an option using the on chip Intel graphics instead of the Invidia add-on graphics.  

Agreed (as I mentioned above).

But some of this aside until you can access the laptop's BIOS again and things like F12-Boot-Menu.

I'm thinking like Safe-Mode, no boot-drive, like pulling batteries, or whatever to get a RTC/CMOS reset ... something like that.

@qsg001​ 

When I am running W11 and I type the command  

shutdown /r /fw /t 0

it reboots into my BIOS.

Similarly if I type

sudo systemctl reboot --firmware-setup

in Linux Mint it restarts into my BIOS.

Have you made it 800 x 600 to view the screens.

~~~~~~~~~~~~

Your system must run GRUB 2.14+, UEFI mode, 

But if you have a halfway house with Legacy mode then maybe that needs curing first.

@qsg001​ ,

I like these slightly older Dell Precision Laptops. While they are a bit larger back then, I like that they were built-inside more like laptops back then (less like smartphones, as the new ones are).

Once you get past this BIOS/Posting/Video issue, and get back to Linux ... just be sure your distro supports dual-GPU's. I know Ubunti-v25 does (as I have a Windows-11/Ubuntu-v25 Dual-Boot setup on my Aurora-R6).