You want to check whether the BIOS has a password on it. Most corporates use one but don't reset it at end of life and after the T420 you can't reset it without replacing the main board.
That's a really important point. To amplify on it, every ThinkPad has as many as three BIOS passwords: the hard drive password, the power on password, and the supervisor password. (Maybe even more than three, as individual hard drives/SSDs could have different passwords.)
The supervisor password is the one you care the most about.
You may get a seller who says "no BIOS password, boots up without a password." But the machine may still have a supervisor password, and if you don't have that you can't change the BIOS settings.
Always make sure there is no supervisor password, or the seller gives you the supervisor password.
The supervisor password is the one you care the most about.
You may get a seller who says "no BIOS password, boots up without a password." But the machine may still have a supervisor password, and if you don't have that you can't change the BIOS settings.
Always make sure there is no supervisor password, or the seller gives you the supervisor password.