Windows 10: Why does Command Prompt restart my pc when I open it from the startup menu?

My Rest this PC option will not work, I am watching a tutorial on how to fix it and I need to access this version of CMD to try this fix. I hold shift and press restart to go into the start up menu, I click Command Prompt and my pc just goes black and a few seconds later I'm on the sign in screen. I don't know what to do.

:)

 

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?

 

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?

 

Windows 10 PC crash and startup failure

Hello,

I suggest you to try the following steps and check if it helps.

DISM:

• 
  Open command prompt by pressing Windows key + X and selecting “Command prompt admin”.
  
• 
  In command prompt, type the following commands and press Enter after each command:
  
  DISM.exe /Online /Cleanup-image /Scanhealth
  
  DISM.exe /Online /Cleanup-image /Restorehealth
  

• 
  Close the command prompt and restart the PC and check if it works.
  

Thank You.