Plug the device into your computer. Hold the power and home button together for 10 full seconds. Your screen should now be black. After 10 full seconds and a black screen, release the power button
but keep holding the home button until iTunes recognizes your device in Recovery Mode once again. Your computer should also recognize new hardware being plugged in at this point as well. Your screen on your device should now be pitch black as if it's turned off or on standby. When restoring, since you're downloading the IPSW already, hold shift (Windows) or command (OS X) and click on the "Restore iPad..." button. Point it to the 7.0.4 IPSW that you've downloaded, and let iTunes do its thing.
Essentially follow this guide
here.