Here are steps of disabling UEFI secure boot in Toshiba laptop: Power on the system and while the “TOSHIBA” logo appears, press F2 key to enter the BIOS Setup Menu.
In the BIOS Setup Utility, change the boot mode from UEFI mode to legacy BIOS mode (or CSM boot mode), and disable the Secure Boot option.On Computers, the Basic Input Output System (BIOS) is an essential low-level software that sits on one of the chips of the motherboard, and it's responsible for basic operations, such as booting.As soon as it starts to boot from the hard drive, hold down the Shift key to make the Grub menu appear. Press Ctrl-D to save your changes to that file. sudo cat > /etc/grub.d/40_custom menuentry 'Dell BIOS Flash Updater' 10.For ease of access, I've uploaded his BIOS here, along with a nicer BIOS logo and a method to downgrade from versions 1.48. Lenovo has never bothered to release a patch, but Oleh and later BDMaster from BIOS-Mods released a custom BIOS fixing the issue. This most likely stems from a lack of support in BIOS for 16 MHz memory modules.
