I own a Flame developer reference phone that runs Firefox OS and have been playing with it for a couple of weeks. The Flame is a fully unlocked device: you have access to the bootloader and can change the firmware. Unfortunately, like me, you may fail to flash the firmware. But as we will see, you can still recover your phone.
Fastboot to the rescue
I tried to upgrade my Flame device to a newer version but the upgrade failed for an unknown reason. Even worse, my phone did not boot correctly after the failed upgrade: it was blocked after the "animated fox" appeared on screen. Thus I could not even use my Flame to phone...
In such a situation, the solution is to boot the Flame in fastboot mode. For that, you have to press the right combination of keys to instruct the bootloader to enter fastboot mode. For the Flame, you should press power and volume down at the same time.
After pressing power + volume down, your Flame device should
boot and display the "Thundersoft" red logo. Plug your phone to your
computer with the USB cable and invoke the
fastboot utility in a
$ fastboot devices 1da25746 fastboot
Great! Your device has entered fastboot mode and is ready to be flashed with the original Firefox OS firmware.
Flashing the original Flame firmware
The procedure to flash the original Flame firmware is described in
updating your Flame's
the base image named
(Update march 2019: the URLs of the base images mentioned in the
documentation are dead, but several Firefox OS enthusiasts keep sharing base
and decompress it. The archive contains a shell script called
flash.sh that you will need to edit. I commented out some lines in
order to skip the instructions executed before
# adb kill-server # adb devices # adb reboot bootloader fastboot devices
After running the script, my Flame phone was fully restored and I could enjoy it again (and even use it as a phone)!