Think of it as a "master key" for Windows. It allows technicians to work on a computer even if the main OS is corrupted, infected, or locked behind a forgotten password.
Geek Squad has a licensing deal with (and historically Kaspersky/Sophos). The MRI contains an offline suite called Falcon . Because the MRI boots outside of Windows, it can see rootkits and bootkits that hide inside the Windows kernel. A standard antivirus running in Windows cannot delete a file that is currently in use; the MRI can, because Windows isn't running. geek squad mri tool