L4T 21.5 on Jetson TK1

Hi akkurrab,

Please following below steps to flash image:
$ sudo tar xpf Tegra124_Linux_R21.5.0_armhf.tbz2
$ cd Linux_for_Tegra/rootfs/
$ sudo tar xpf …/…/Tegra_Linux_Sample-Root-Filesystem_R21.5.0_armhf.tbz2
$ cd …
$ sudo ./apply_binaries.sh

OR you can try to install via JetPack3.0.
https://developer.nvidia.com/embedded/dlc/jetpack-l4t-3_0