Windows 10: Dell boot device options screen only flashing underscore

So I was trying to boot off of my usb to run Ubuntu off of it, but I pressed F12 and there was only a flashing underscore on the top left hand corner of the screen. I waited for a few minutes and nothing appeared. Please help!

:)

 

Blank screen with flashing underscore

Hi,



Thank you for writing to Microsoft Community Forums.



I appreciate the efforts taken by you in resolving the issue. I understand that you get a black screen with flashing underscore. I’ll certainly assist you with the issue.



However, please let us know the make and model number of the computer that you are using.



As you have already tried changing the Boot order, I would suggest you to refer the troubleshooting steps mentioned below and see if that helps.



Method 1: Rebuild BCD



You may want to try rebuilding the BCD file and see if that helps. Refer the steps mentioned below:

1. Create a bootable media and boot the PC using the
   media.
   
2. On the initial setup screen, select the language and other
   preferences and click on Next. (If you don't see the setup screen, your PC might not be set up to boot from a drive. Check your PC manufacturer's website for info on how to change your PC's boot order, and then try again.)
   
3. Now, click on Repair your computer.
   
4. On the System Recovery Options screen, select
   Troubleshoot> Advanced options > Command Prompt.
   
5. Now type in the commands and hit enter: BOOTREC /FIXMBR
   
   BOOTREC /FIXBOOT
   
   BOOTREC /scanos
   
   BOOTREC /rebuildbcd
   
6. Restart the PC.
   

Method 2: Startup Repair



If Rebuilding BCD doesn’t help, we can perform a Startup Repair on the computer and check. Refer the steps mentioned below:

1. Boot the PC using the bootable media.
   
2. On the initial setup screen, select the language and other
   preferences and click on Next. (If you don't see the setup screen, your PC might not be set up to boot from a drive. Check your PC manufacturer's website for info on how to change your PC's boot order, and then try again.)
   
3. Now, click on Repair your computer.
   
4. On the System Recovery Options screen, select
   Troubleshoot> Advanced options > Startup Repair.
   
5. Restart the PC.
   

Let us know how it goes.



Regards,

Nikhar Khare

Microsoft Community - Moderator

 

Boot options

Hi Its

Have you created a bootable Windows installation USB drive?

If so, connect that to your laptop

Boot up your laptop and on the Dell logo screen, repeatedly press F12 to bring up the Temporary boot menu

From there you should be able to choose to boot form that USB device

If not, on the Dell logo screen, repeatedly press F2 to boot into BIOS

From there look for the boot priority list and move the flash drive to the top of the boot order list, press F10 to save that and restart your laptop

If the above does not work for you, try another USB port on the opposite side of your laptop - Dell's sometimes only boot from one of the USB hubs . . .

If none of the above works for you, please post photos of the options you have in BIOS

 

Black screen with flashing underscore

The blinking underscore normally means your system is being directed to boot in such a way the process cannot be completed.

If you can get into the bios, make sure the Windows Boot Manger (if UEFI) is the primary boot device, and not a drive. Edit: If not UEFI then you would need the actual drive set as primary boot device.

If some type of OS install was attempted, what was it?

If any settings in the Bios were changed, what were they?