it is the latest JetPack SDK release, JetPack-4.5.1 to added support for using Jetson TX2 NX module with reference carrier board included in Jetson Xavier NX Developer Kit.
you may use SDK Manager for flashing Jetson TX2 NX module on a Jetson Xavier NX Developer Kit reference carrier board.
there’s flash configure file, jetson-xavier-nx-devkit-tx2-nx.conf to enable JetPack-4.5.1 for flashing TX2 NX.
thanks