I seem to be having a Similar problem to DN66:
Used my N10 quite a bit last night with no problems, last thing I did before I went to bed was told it to install the 10 pending app updates, closed the case lid and when to bed.
This morning I went to use it and it was having trouble connecting to my WiFi so I rebooted using the menu reboot.
This is when the troubles started.
I wasn't really paying attention as it rebooted, but I noticed after 5 or 10 minutes that it was still at the "Google Screen". This being much longer than usual for a reboot, I forced another restart by holding the power button to get the same result.
Booted into the bootloader and selected recovery. I was showing the TWRP screen for about a minute before it returned to the Google boot screen, then gave me the Nexus "X" for booting, but then gave me a "Enter password to Decrypt"...only problem is that my device is not encrypted.
Tried a couple random passwords with no luck, used the power menu again. Tried Recovery again where it keeps hanging at the TWRP boot screen with no progress until back to the "Google" screen.
I have no tried to use Wug's NRT as well as the Nexus 10 Toolkit to try and restore the tablet. With Wug's it says that it has flashed the stock imgage and to wait for it to reboot, but the Nexus doesn't indicate that it ever connected with the computer. With the Nexus 10 Toolkit I have tried to flash stock image as well as flash stock recovery.
When flashing stock image, it gets to the point where it sends the bootloader, succeeds, then hangs at "Writing Bootloader" and the N10 shows "Fastboot Status - flash:bootloader".
When flashing stock recovery, it sends recovery successfully but then hangs at "Fastboot Status - flash:recovery".
It seems that my device is having problems any time it tries to access and/or write to the device.
Any thoughts?
Edit: Running AOKP latest MR2