Switch that off (!) in the cmd (admin) command: powercfg /h off. 2. Secure Boot in BIOS. when an option is greyed out it usually indicates that you have to change certain settings before you can activate it. (see manual) It is also possible that you don't have the administrative "rights" to make the change. Hey guys this is my first time installing windows 10.I made a bootable usb using microsoft media creation tool on a usb 3.2.When i restart and go to boot device options it shows 3 options: 1.Os boot manager (uefi)-windows boot manager (my ssd name) 2.USB Hard drive (UEFI)-USB. 3.Boot from UEFI file. System Configuration > Boot Options > Legacy Support or Boot Options > legacy Support ; If Legacy Support is DISABLED, skip to Procedure 3, Step 3. If Legacy Support is ENABLED, change it to DISABLED, save the changes and exit, then go to Procedure 3. Turn off your device and remove all power cords from it. If on desktop, remove any residual power by pressing the power button for at least 10 seconds. Now, carefully remove the side panel to get access to the internals of the computer. Check for any disconnected, misaligned or damaged wires. HP Pavilion 15.6 inch Laptop PC 15-eh1000 (2H5A6AV) Got a brand new HP laptop with latest BIOS installed. I tried booting Linux - Puppy, Ubuntu, Mint, Fedora - all have the same issue - "The selected boot device failed." Used Rufus to make the USB and tried both MRB and GPT. Disabled Secure Boot. Tried both USB ports. None of this worked. Method 2: Add Linux boot entry in the boot settings. Many people encounter another common issue: the absence of Linux grub entry from the boot options. This means that there is only Windows, no Linux option in the boot settings. If it is the same case with you, go to BIOS settings. Following are the settings which solved my problem -. Advanced\PCH Storage Configuration\Sata mode selection - AHCI. Advanced\Onboard Devices Configuration\PCIE Express Slot and M.2 Bandwidth - M.2 mode. Boot\Fast Boot - disabled. Boot\CSM\Launch CSM - Enabled. Boot\CSM\Boot Devices Control - UEFI and legacy. In System Information: BIOS Mode: Legacy. According to the lit Microsoft's MBR2GPT.exe tool converts disks from MBR partition to GPT and configures system partition for UEFI boot. It doesn't support configuring firmware mode. Switching firmware to UEFI mode requires manual configuration in the firmware menu. Microsoft's doc and a video is here xifS.