How to Unlock ALLDOCUBE T12 for flashing with fastboot on Linux?

Hello. I am tryed to flash my tablet PC using this commands with fastboot and i have got this dump

[gri@gribrook fplaye]$ cd T12_V1.0_20170222/
[gri@gribrook T12_V1.0_20170222]$ ls
boot.img Checksum.ini FlashToolLibEx.dll lk.bin OTA secro.img
cache.img DB FlashToolLib.v1.dll logo.bin preloader_joyasz8321_tb_m.bin system.img
CheckSum_Gen.exe Flashtoollib.dll items.ini MT6580_Android_scatter.txt recovery.img userdata.img
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot devices -l
0123456789ABCDEF fastboot usb:2-3
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot getvar all
(bootloader) max-download-size: 0x8000000
(bootloader) partition-size:userdata: 32000000
(bootloader) partition-type:userdata: ext4
(bootloader) partition-size:cache: 10000000
(bootloader) partition-type:cache: ext4
(bootloader) partition-size:system: 80000000
(bootloader) partition-type:system: ext4
(bootloader) partition-size:metadata: 2660000
(bootloader) partition-type:metadata: raw data
(bootloader) partition-size:nvdata: 2000000
(bootloader) partition-type:nvdata: ext4
(bootloader) partition-size:frp: 100000
(bootloader) partition-type:frp: raw data
(bootloader) partition-size:expdb: a00000
(bootloader) partition-type:expdb: raw data
(bootloader) partition-size:logo: 800000
(bootloader) partition-type:logo: raw data
(bootloader) partition-size:para: 80000
(bootloader) partition-type:para: raw data
(bootloader) partition-size:keystore: 800000
(bootloader) partition-type:keystore: raw data
(bootloader) partition-size:secro: 600000
(bootloader) partition-type:secro: raw data
(bootloader) partition-size:oemkeystore: 200000
(bootloader) partition-type:oemkeystore: raw data
(bootloader) partition-size:recovery: 1000000
(bootloader) partition-type:recovery: raw data
(bootloader) partition-size:boot: 1000000
(bootloader) partition-type:boot: raw data
(bootloader) partition-size:lk: 60000
(bootloader) partition-type:lk: raw data
(bootloader) partition-size:seccfg: 40000
(bootloader) partition-type:seccfg: raw data
(bootloader) partition-size:protect2: a00000
(bootloader) partition-type:protect2: ext4
(bootloader) partition-size:protect1: a00000
(bootloader) partition-type:protect1: ext4
(bootloader) partition-size:nvram: 500000
(bootloader) partition-type:nvram: raw data
(bootloader) partition-size:proinfo: 300000
(bootloader) partition-type:proinfo: raw data
(bootloader) partition-size:preloader: 40000
(bootloader) partition-type:preloader: raw data
(bootloader) off-mode-charge: 1
(bootloader) warranty: yes
(bootloader) unlocked: no
(bootloader) secure: yes
(bootloader) kernel: lk
(bootloader) product: JOYASZ8321_TB_M
(bootloader) version-preloader: 0.1.00
(bootloader) version: 0.5
all: Done!!
Finished. Total time: 0.077s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flash boot boot.img
target reported max download size of 134217728 bytes
Sending ‘boot’ (7906 KB)…
OKAY [ 0.373s]
Writing ‘boot’…
FAILED (remote: download for partition ‘boot’ is not allowed
)
Finished. Total time: 0.390s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock

OKAY [ 15.504s]
Finished. Total time: 15.512s
[gri@gribrook T12_V1.0_20170222]$
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot getvar unlocked
unlocked: no
Finished. Total time: 0.009s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_critical
OKAY [ 7.630s]
Finished. Total time: 7.635s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot getvar unlocked
unlocked: no
Finished. Total time: 0.010s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing get_unlock_ability
(bootloader) unlock_ability = 0
OKAY [ 0.010s]
Finished. Total time: 0.017s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_critical
(bootloader) Start unlock flow

FAILED (remote:
Unlock operation is not allowed
)
Finished. Total time: 7.331s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_critical
OKAY [ 4.843s]
Finished. Total time: 4.851s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot getvar unlocked
unlocked: no
Finished. Total time: 0.011s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_bootloader_nonce
fastboot: usage: unknown ‘flashing’ command unlock_bootloader_nonce
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing get_unlock_bootloader_nonce
FAILED (remote: unknown command)
Finished. Total time: 0.010s
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_bootloader
fastboot: usage: unknown ‘flashing’ command unlock_bootloader
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_bootloader 12
error: could not load ‘unlock_bootloader’: No such file or directory
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot flashing unlock_bootloader
fastboot: usage: unknown ‘flashing’ command unlock_bootloader
[gri@gribrook T12_V1.0_20170222]$ sudo fastboot getvar unlocked
unlocked: no
Finished. Total time: 0.011s

What i am doing wrong.  I pressed power+volumeup and catch a menu

[Recovery Mode]

[Fastboot Mode]  <==

[Normal Boot]

When i tryed to do (sudo fastboot flashing unlock)  i`ve got

 

Please help me repairing this gadjet.

the picture metion you press volume up button to confirm unlocking.

by the way ,there is a linux version mtk spflashtool you can run on linux os to flash the firmware:

https://androidmtk.com/smart-phone-flash-tool