B2G flash-flatfish error

Start the flash-flatfish.sh procedure.

--- Image files checking ---
Good, image files are in position now.

--- Check to see if the adb works properly (for Android 4.2 and above) ---
'adb' works fine.

--- Check to see if the flatfish device is ready ---
Oh, the flatfish device is not there, or is not turned on in a mode where 'adb' can be used.

--- Let's see if it's already in the fastboot mode ---
Error: Fastboot mode is not detected. Check to see if the device is not turned on.
*Note: If it is powered but both 'adb' and 'fastboot' could not work,
       please check to see if the device has become brick. (Bug 1026963)

=== Usage ===
Usage: flash-flatfish.sh [-h] [<path_to_images> [<path_to_b2g_root>]]
Options:
  -h: help
  <path_to_images>: default to ././
  <path_to_b2g_root>: path to the root of the B2G source, for using 'adb' only.  If 'adb' can be found in $PATH, this option can be ignored.
Example:
  1. Run in B2G root directory.
    $ flash-flatfish.sh
  2. flash images in the current directory
    $ flash-flatfish.sh .
  3. flash images in ~/flatfish-images
    $ flash-flatfish.sh ~/flatfish-images
  3. flash images in ~/flatfish-images, and specify the source path of B2G for using 'adb'
    $ flash-flatfish.sh ~/flatfish-images ~/dev_fxos/a31-b2g