The USB key method cannot be used once the password has been changed from the default admin password. Although there are facilities in the SCS to specify a new default password in the USB key file, the feature is not support by the BIOS. This means the USB key method is only available for first-time provisioning after box arrives from the OEM. If the box has been un-provisioned, or its password has been changed, then the USB key method is no longer available as an option.
For anyone who needs to use the USB key after changing the default password, we were able to reset the password to admin by resetting the BIOS. We reset the BIOS by removing the battery on the motherboard.