My PRS-505 seems to have locked up.
I was looking at a few books, then I went back to the book I was reading, clicked "Continue Reading" and nothing happened. The screen remained on the main index of the book as though I had not pressed the "1" button to continue reading.
Now it is not responding to any button presses, including the power-off button.
Any ideas how to wake it up, or how to force a reboot?