Nexus 7 bricked by 4.2! Replacement on the way.
My son played angry birds till the battery died and put it on the shelf without recharging. When I picked it up and hit the power button, it immediately went into shutdown due to dead battery. After charging all night, all attempts to restart failed fantastically. First I would see the Google splash screen followed by the "X" screen and get stuck there. Then subsequent attempts to reboot were followed the Google screen to "X" screen to a screen displaying static or snow and get stuck there (never seen that before). Then after powering down and back up with long power button presses, it would then just go to faint blue background illumination and get stuck there, not even the Google screen or "X" screen. Tried hard resets, long power button presses, display now only flashes between faint background illumination and total black every 5 seconds or so.
Called Google customer support this morning (called ASUS first, big mistake, dont waste your time) they didnt sound very surprised. Said they know of this type of issue with very early devices (ordered my Nexus day 1). Long story short, new one in the mail today. He mentioned that they are working on getting a fix out there for this problem, but its not ready yet. So if you were an early device purchaser, you may want to wait before installing 4.2, mine was the 8 GB version.