On USB stick will have 4 files
bootargs.bin
fastboot.bin
recovery.img
update.zip
bootargs.img, fastboot.img, recovery.img extract from update.zip
bootargs.img rename as bootargs.bin
fastboot.img rename as fastboot.bin
recovery.img, update.zip just copy.
Pay attention of Windows Explorer not to hide know extension then will make proper rename of extensions files.