Did you update the firmware on a Windows PC? That is the only way I know of to update the firmware of a 400 Series camera at present, as a firmware updater tool for Linux is still in development and coming soon.
The release notes for the firmware make reference to your lsusb non-detection issue. They say: "The frequency of the problem occurrence depends on specific Kernel version. It occurs more frequently on 4.4.0.x kernel versions and less frequently with 4.10.x kernel versions". The recommended workaround is to unplug the camera and plug it back in. Be sure to push it in firmly and quickly, and not push it in slowly.