Windows 10: How do i register my laptop with Microsoft so I can unlock it?

I thought I lost my Asus Vivobook laptop and locked it from my Microsoft account. Found the device and tried to unlock it but couldn't figure out how at first and accidentally unregistered the device from my Microsoft account. I tried to reregister so I could unlock it using my Microsoft account but it won't accept the device serial number. How can I register my laptop and/or unlock it? The dialogue that comes up on laptop says "To sign in, make sure your device is connected to the Internet, and have your administrator sign in first." When I try to register the device with Microsoft, it says,

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register PC with microsoft; use local account to log in

I bought a used laptop running Win 10 Pro. winver reports 1809.
How do I register my PC with my Microsoft account?
But when I'm done, I'd like to use my local account each time to log in.
Please tell me how to do that.
I am very new at Win 10, and need step by step instructions.

Thanks,

 

Laptop not recognising passcode

Hello,

For us to assist you with your query, we will appreciate it if you can answer the following questions:

• Are you unable to unlock your device?
• Is it a Microsoft or a local account?
  
• Are there any recent changes in your device?
• What troubleshooting steps have you done so far?

In the meantime, we suggest that you reboot your laptop and make sure that Caps Lock is off when you enter your password.

Looking forward to your response.

 

Best laptop under $800??

Well the last one I suggested seems to be the best for 650$

EDIT: to facilitate your search...

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