Might the the battery got real low.
Have you tried a reset ? There is a combination of key. If I remember right, press menu then back hold them until the cybook restart. (Read the manual it's written in there)
There is an hardware button too for emergencies.
If the cybook wasn't off, but crashed , it's possible it's using the battery, make sure tu recharge.
Last edited by EowynCarter; 10-02-2011 at 02:05 PM.