Recently purchased 100 devices and have an issue with one of them. Device booted up normally at first and I was able to access Wifi & log in to my gmail account. Got to the main screen and applied the Wireless Update as prompted. After the update finished, the device showed an icon of an Android droid that had fallen over with the text "No Command". I could do nothing from that page. I restarted the device and it is showing the text "=> FASTBOOT mode...". I have restarted in recovery mode and tried performing a Wipe data/factory reset but that didn't help.

I'm stuck and the device is useless right now. Any way to resolve this?

Hi there! so the issue is still present after a factory reset made from the recovery mode menu? 

Yes, even after a factory reset, the problem is not resolved. I restart the device and get the initial "Blackview... Powered by Android" startup screen and then after a few seconds the screen is black with the text "=> FASTBOOT mode..." at the very bottom. Nothing else happens. See image below

https://www.dropbox.com/s/gd6pagpdx4si906/IMG_3455.JPG

How can I fix this?

This may be helpful!
https://www.recoverandroid-data.com/blog/fixed-android-stuck-in-fastboot-mode

I tried all three suggestions on that page. No matter what I did, the device would only reboot and show "=> FASTBOOT mode...". Nothing worked. 

How can I resolve this?

Unfortunately it looks like you'll have to contact your seller to have it replaced under warranty. The update corrupted the system, flashing again the firmware may solve the issue, but firmware files for flashing are still not available for such phone model.