What you did:
fastboot reboot bootloader
That's wrong. It's
You only flashed stock kernel which is not compatible with DU ROM hence the bootloop.
Never mind. Just turn it off by holding power button. As soon as the ...
Use this tutorial its helped me in past hope it will help you also>http://forum.xda-developers.com/google-nexus-5/general/tutorial-how-to-flash-factory-image-t2513701 Thanks to> abaaaabbbb63
Thats what i did......