Black firmware lock screen

Hello,

When you set a firmware password, users who don't have the password can't start up from any disk other than the designated startup disk.

If you can't remember your firmware password, schedule an in-person service appointment with an Apple Store or Apple Authorized Service Provider. Bring your Mac to the appointment, and bring your original receipt or invoice as proof of purchase.

Thanks for reaching out!

-Drake

I would suggest first calling the Apple Store or AASP to confirm what paperwork you need to bring to provide valid proof of purchase and personal ID so you have the necessary paperwork when you arrive.