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For anyone having difficulty getting the cmd to run on the login screen follow this method https://youtu.be/bTAOmP7k3LQ.
It 100% worked for me. After rebooting it asked me for my password so I just used my Microsoft account password to log in. Don't know how it would work for local accounts since it still didn't allow me to enter my pin.
I was starting to give hope as well. Another method you can try is this, [Fix] Disabled all services in MSConfig (System Configuration utility) - Your Windows Guide. Using the on-screen keyboard to run cmd but not sure if this works.
Some more info on my situation Something happened and your PIN isn't available Windows 10 error - Microsoft Community
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