Redbox Desktop is an application accessible via a keyboard combination or by pressing the “Control Panel Log In” button from the Field Maintenance Application.
This is an advanced admin panel containing low level access to the OS, including an Admin command prompt, File Explorer, various hardware and administrative software tools, as well as the ability to stop/start most processes on the machine.
On machines that are Offline (all kiosks are), the login screen for the desktop (titled “Redbox Control Panel Login” will accept any credentials. No modifications are required.
This appears to be an intentional backdoor in the software to allow easy maintenance operations on the kiosk, even if the kiosk doesn't have an active connection to Redbox's services.