How can I unlock my MacBook Air after a factory reset?

A slightly old and technical discussion but it may be what you are encountering. Enter a password to unlock the disk maci… - Apple Community

I also got this from another discussion board. It received many posts of appreciation:

I turned off the wifi

I clicked on cancel

a popup should appear, click on "startup disk"

once the startup disk options show, click on the red "x" button at the top left of the popup.

it should show the recovery mode.

I first clicked on disk utility and erased all data on my disk drive which was the Macintosh HD.

then, I clicked on download Sonoma (this is the latest update for me as I'm writing this.)

Then it should boot up perfectly fine after downloading the Sonoma.

"i tried to factory reset my mac but now it is stuck saying enter a password to unlock: i tried to factory reset my mac but now its keeps telling me to enter a password to unlock the disk. When i do (using the correct password) it restarts and gives me the exact same message over and over again."

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Try Formatting this Once More:

Obviously, it is encrypted. So, boot in Recovery Mode > go into Disk Utility > Select the drive > reformat this.