Windows 10: What is the password for the command prompt in reboot?

I am switching my Bios from Legacy to UEFI and I need to use my command prompt during the boot. I tried my PIN when I unlock my computer and my Microsoft Account password but neither have worked.This is an example pic from google.

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command prompt will not open in safe mode with command prompt

I am repairing a laptop for a friend and I need to access windows in safe mode and the owner has forgotten the password to the main user. I tried logging on with the administrator profile in safe mode but it is not showing up so I was going to use command prompt in safe mode with command prompt but command prompt will not open when I boot that option. Does anyone have any hints for me to figure this out?

 

command prompt will not open in safe mode with command prompt

Would I just follow the same steps within safe mode after hooking up to the other system?

 

Installation media boots to command prompt

I've just booted from known working install media to see exactly what it does when booting. The sequence of events is...

1. Windows logo on a black screen
2. circling dots appear beneath the logo
3. light blue 'Please wait' screen with circling dots
4. a command prompt window (very briefly)
5. the initial Setup page appears

Do you see steps 1-3? If so, it appears you have stopped at step 4, suggesting that something on the disc cannot be read.

Does the disc boot properly in another machine? If so, try cleaning the laptop's drive lens then try booting from the disc again.

If not, make new install media with Microsoft's Media Creation Tool, either as a bootable USB, on an ISO that you can burn to another disc. At Step 8 in Option One of this tutorial you can choose between making a USB or an ISO.

Download Windows 10 ISO File