@Clark21
I reviewed your post and I understand that the computer is not booting to Windows and you are getting a bluescreen error on startup.
Don’t worry, I assure you I will try my best to get this sorted.
The 0xC000021A error is a Blue Screen of Death or BSoD error that occurs when a Windows user-mode subsystem is compromised. To resolve this issue, you need to perform a recovery on the computer and this will reinstall the operating system.
Follow the steps in the below article to perform a recovery on the computer.
https://support.hp.com/in-en/document/c06162205
Let me know how it goes and you have a great day!
P.S: Welcome to the HP Support Community 😊
If you wish to show appreciation for my efforts, mark my post as Accept as Solution. Your feedback counts!
Cheers!
Stay Home – Stay Safe
The_Fossette
I am an HP Employee