Hi Alecscreenname, welcome to the HP Forums. I understand that you are caught in an Automatic Repair loop generating error 0xc000021a.
I have found an article specific to your symptoms, which will help you to troubleshoot this issue. Start with "Method 1: Safe Mode + Clean Boot combo" here: Fix STOP Error 0xc000021A – Cannot Start Computer in Windows 8 (8.1)
Let me know if you are able to get passed this.