flash_imageを使用したflash update.img -- updates フィールド と rom-flashing フィールド と shell フィールド android 関連 問題

I want to flash a new ROM using the shell. (Need this later to do per app so there is no other way than shell). Here is what I tried

connected to 192.168.1.9:5555 Pauls-MacBook-Pro:~$ adb shell root@android:/ # su root@android:/ # flash_image usage: flash_image partition file.img root@android:/ # flash_image boot /mnt/sdcard/_updateboot.img error opening /mnt/sdcard/_updateboot.img: No such file or directory 1|root@android:/ # flash_image boot /mnt/sdcard/_update/boot.img                root@android:/ # flash_image misc /mnt/sdcard/_update/misc.img                  root@android:/ # flash_image kernel /mnt/sdcard/_update/kernel.img              root@android:/ # flash_image recovery /mnt/sdcard/_update/recovery.img          root@android:/ # flash_image system /mnt/sdcard/_update/system.img              mtd: write error (No space left on device) error writing system: No space left on device 1|root@android:/ # flash_image system /mnt/sdcard/_update/system.img            mtd: write error (No space left on device) error writing system: No space left on device 1|root@android:/ # reboot 

Even if I don't get the No space error it just wouldn't boot (it is a TV dongle, so no HDMI output). Has anyone an idea how to flash ROMs from an ROM?