I've started playing God of War: Chains and Olympus yesterday, and I'm seriously enjoying it. Ready at Dawn did a great job.
However, it seems to, uh, have done something to my Vita. The game froze. I was still able to return to the Vita's main menu, but when I closed the game and started it again, the screen stayed black. After closing and restarting the game a second time, the screen was still black, but I wasn't able to return to the main menu anymore. When I pressed the home button, a warning icon appeared in the top left corner.
So I tried to turn it off. After tapping the "Power Off" button, the activity indicator in the center of the screen just kept spinning for a few minutes. Finally, the screen went black, but the home button is still glowing blue, which means it's still turned on.
edit: Figured it out. After holding the power button for some time, it went into Safe Mode. From there, I simply chose "Restart System", and now it's working again. The game's working, too. It's weird, though: I just learned that in order to launch Safe Mode, you're actually supposed to hold the Power Button, the PS Button and the R Button at the same time. Well, whatever.