Host doesn't recognize the device in fastboot

Hello there,
I’m trying to install a new kernel in my dragonboard 410c using another host PC.
I’ve done all the steps mentioned in this forum, and when I run the “fastboot…” command, I keep getting “Waiting for devices…” from the host PC.

What do I need to do in the device side in order for the host to recognize it?
Thanks in advnace.

To put the board in fastboot mode you need to power it off, hold down the S4 button, then apply power. And make sure the USB host switch on the bottom of the board is off.

It worked! Thanks a lot