Dell Precision M2400 (Mid 2008) - Manual (Page 80)

A number
A special (nonalphanumeric) character, such as !, $, or ; excluding the :, ", and , characters.)
The underscore ( _ ) and spacebar are valid password characters but do NOT add to the password complexity.
5. Change the password to establish Intel AMT ownership.
The computer then goes from the factory-default state to the setup state.
6. Select Intel ME Configuration, and then press <Enter>.
ME Platform Configuration allows you to configure ME features such as power options, firmware update capabilities,
and so on.