Hi ana gineste,
Thanks for reaching out to Microsoft Q&A Forum. I understand you are unable to set up your PIN after disabling Secure Boot and are stuck in a repeated PIN setup error loop.
Please make sure you have already tried the steps suggested by Q&A Assist. In addition, please try to follow these steps:
1, Restart your PC and enter BIOS or UEFI settings, then re‑enable Secure Boot, save changes, and boot back into Windows.
2, On the sign‑in screen, select Sign‑in options, choose Password, and sign in using your Microsoft account password.
3, Once signed in, open Settings, go to Accounts, then Sign‑in options, remove the existing PIN, and restart the device.
4, After restarting, go back to Settings, Accounts, Sign‑in options, select Windows Hello PIN, and set up a new PIN.
5, If the issue continues, restart the device into Safe Mode, sign in with your password, then repeat step 3 and step 4 from Safe Mode, and restart normally.
6, After successfully setting the PIN, you may turn off Secure Boot again if required.
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