Default [Q] Soft bricked after failed CM 11 install

Hi

I'm looking for some advice on the best way to recover from the following. After a failed CM11 install, my phone has fastboot with CWM 6.0.4.7 installed.

What is the best way to either go back to stock and try again or install a CM11 image

Is there a way to use fastboot to copy a zip image to the phone?
trying root# ./fastboot flash /sdcard/ /home/grahams/Downloads/cm-11-20140224-NIGHTLY-falcon.zip
but getting errors

sending '/sdcard/' (226084 KB)...
OKAY [ 10.201s]
writing '/sdcard/'...
(bootloader) Permission denied
FAILED (remote failure)
finished. total time: 10.221s


Is there a good tool for reimage the phone (Linux perfered)?

thanks in advance