how to check the bootloader locked or unlocked?

hello guys,
i rooted my phone, but it has a display mistake and i will send it to zte.
i flashed the original stock rom with twrp, and i flashed the stock recovery with twrp! with adb and fastboot not working!!


FAILED (remote: unknown command) by any commands, example: fastboot flash recovery recovery.img the failure!



C:\Program Files (x86)\Minimal ADB and Fastboot>adb devices
List of devices attached
364f5261 device


C:\Program Files (x86)\Minimal ADB and Fastboot>adb reboot bootloader

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot devices
364f5261 fastboot

C:\Program Files (x86)\Minimal ADB and Fastboot>fastboot oem device-info
...
FAILED (remote: unknown command)
finished. total time: 0.016s

i dont know if my bottloader is locked or unlocked and i must locked it because i want to sent my device to zte!

any ideas?

thank you very much
my device axon7 2017G.

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