This mode allows to always make ON your Tablet whet it powered off
Download the SDKon this page and extract (preferably to c:\).

Press and hold volume up + volume down + power. The N7 should boot into fastboot mode (if that doesn't work, try pressing volume down + power).

Open the directory and find "platform-tools" folder. Don't open it. Press shift + Right click folder -> "Open command window here"

Then enter the command: fastboot oem off-mode-charge 0

If everything went ok... you should have your N7 booting when powered.