https://4pda.to/forum/index.php?showtopic=598421&st=3440#entry39475586
https://4pda.to/forum/index.php?showtopic=598421&st=2460#entry38509111
http://web.archive.org/web/20211203224830/http://builds.firefoxos.mozfr.org/
http://web.archive.org/web/20170606235952/http://builds.firefoxos.mozfr.org/doc/fr/devices/zte-open-c-fr
(about this last link, forget about "Open C Upgrade Tool", flash ffos with 
qpst emmc software download)
https://gitlab.com/mossroy/zte-openc-switch-bluedroid