Padlock screen on an old MacBook Air 2015

I bought a new laptop, the M1 one. I was trying to format my old dusty MacBook Air 2015 and I removed it from "Find My" since I do this with my AirPods whenever I want to restart them.

After, I restarted the laptop after tapping "erase" from my iPhone then the padlock screen appears. I tried the trouble shooting steps to get the firmware password but it won't work. It goes directly to the paddock screen.

When I turn it off, it shows a bit of a glitch on the screen, logo then, padlock.

Is there anything else I can do? Can I access frimware password from a different MacBook or on iPhone? I was to be able to open the old MacBook without really spending tons of cash to save an old MacBook. I'm a sentimental person so... please help.