Please use the official method. We don’t guarantee the method on jetsonhacks.
https://docs.nvidia.com/jetson/l4t/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/flashing.html#wwpID0E0HM0HA
or
https://elinux.org/Jetson/L4T/Boot_From_External_Device