I have a ANS F30, which is said to be the same device. I can get it into fastboot mode with volume down + power buttons.
$ fastboot devices
but any fastboot command returns the following error:
$ fastboot flashing unlock
FAILED (remote: 'unknown command')
fastboot: error: Command failed
There is something different about fastboot on these devices, and I don't know what it is. Do Qualcomm chips interface differently with fastboot than with Mediatek chips?