Did you update with the tools from NVIDIA? If you used ordinary Ubuntu to change from an older 14.04 version to the 16.04 version it’ll leave the Jetson unusable until you use the official tools. The generic mechanism from Ubuntu doesn’t understand embedded systems and overwrites the direct hardware access files.
For reference the version of Ubuntu with NVIDIA support is “Linux for Tegra”. The current version for the TX1 is L4T R24.2.1, and supports Ubuntu 16.04 LTS. Downloads for this can be found here:
[url]https://developer.nvidia.com/embedded/linux-tegra-r2421[/url]
Do be aware that the downloads page has a separate login which requires a separate registration…the forum login does not work there.
You need a host PC running Linux to flash a Jetson. If you just use command line any x86_64 standard Linux PC will work. If you use JetPack (a front end for more convenient use) you’ll need Ubuntu 14.04 on your desktop PC host (some people get it to work with Ubuntu 16.04). Sometimes a VM works, but often a VM has issues with USB. In all cases you will need plenty of extra disk space…once everything is unpacked you’ll probably still need another 25GB of spare space to be safe.
There is documentation there on flash, but here is a bit of info if you want to flash on command line:
[url]https://devtalk.nvidia.com/default/topic/982779/jetson-tk1/how-to-perform-a-correct-fresh-ubuntu-install-on-jetson-tk1/post/5040584/#5040584[/url]