mbr2gpt conversion, followed by black screen

Anthony Valdez 0 Reputation points
2026-09-13T06:23:39.9366667+00:00

I needed to convert my system, and it seemed to have been successful until I restarted my PC. Upon powering on, I get nothing but a black screen. I try to open bios but nothing happens. I’ve searched online for answers, but none of the solutions I’ve found have worked.

Windows for home | Windows 11 | Install and upgrade
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  1. AI answer

    2026-09-13T06:23:53.7666667+00:00

    A successful mbr2gpt conversion is not enough by itself. After conversion, the PC firmware must be changed to boot in UEFI mode. If that does not happen, Windows can fail to boot and the system can show a black screen or a blinking cursor because the firmware cannot find a boot device.

    Try this recovery path:

    1. Force the PC off by holding the power button for about 20 seconds.
    2. Start from Windows installation media for the installed version of Windows.
    3. On Install Windows, select Next > Repair your computer.
    4. Go to Troubleshoot > Advanced options > Startup Repair.
    5. Let Startup Repair complete, then shut down and power on again.

    If the system still does not boot:

    1. Boot again from the Windows installation media.
    2. Open Command Prompt with Shift+F10.
    3. Check the MBR2GPT logs. The most detailed logs are:
      • setupact.log
      • setuperr.log
      In Windows PE, the default log location is %windir%.
    4. If MBR2GPT reported success, verify in firmware that:
      • Boot mode is set to UEFI Only or equivalent.
      • CSM is disabled.
      • Secure Boot is enabled if supported.

    Important checks:

    • MBR2GPT.EXE converts a system disk from MBR to GPT without deleting data.
    • After conversion, the firmware must be reconfigured for UEFI boot.
    • The device must support UEFI.

    If the screen is black even when trying to enter firmware setup, use the Windows recovery path above first. A black screen with a blinking cursor can indicate that UEFI or BIOS cannot find a boot device.

    For a general blank screen, these basic checks can also help before recovery:

    • Make sure power and display connections are working.
    • Press Windows + Ctrl + Shift + B to reset the graphics driver.
    • Press Windows + P, then P again, then Enter to cycle display modes.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. DaveM121 929.7K Reputation points Independent Advisor
    2026-09-13T06:57:58.5933333+00:00

    If you have successfully converted your drive to GPT, you need to get into BIOS to disable CSM Support and enable Secure Boot in the Security settings so Windows will boot in UEFI mode.

    If you start your PC now and do not even see the PC manufacturers logo screen or the spinning dots to indicate Windows is attempting to boot up, try using this method to reset your BIOS.

    Disconnect the PC from mains electricity.

    Press and hold the power button on the case of your PC for 30 seconds.

    Wait 30 minutes

    Reconnect the power cable and start your PC, is there then an image on the screen so you can access BIOS.

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