About Vorke Z1 :
Note
OTA firmrware is not rooted, and it comes with ota, but if you flash the rooted firmware, the ota function won’t work.
You can only upgrade Vroke Z1 from Android Marshmallow to Android Nougat by flashing it with PC upgrade firmware below.
Android Nougat
Vorke Z1 PC Upgrade Firmware (root)
http://www.mediafire.com/file/v442zw4wbs29y63/Vorke_Z1-rooted-PC-NMF26Q-20170701.121615.V0321.zip
Vorke Z1 PC Upgrade Firmware (unroot)
http://bit.ly/2qdFKku
Android Marshmallow
Vorke Z1 OTA firmware
http://www.mediafire.com/file/gio8xl9j1v5ugqc/Vorke_Z1-ota-20161124.160846.V0923.zip
Vorke Z1 SD Card upgrade firmware (rooted)
http://www.mediafire.com/file/7p7ujmhrjg9w1c7/VORKE_Z1_20161207_ROOT_SD.rar
Vorke Z1 PC upgrade firmware (rooted)
http://www.mediafire.com/file/9k5r28y1u8008t2/Vorke_Z1-ROOT-PC-MHC19J-20161207.102746.V0923.img