Could the music/mp3 player be running? This is something that is quite common with the 505 unfortunately. The music player will be running in the background without the owner realizing it and draining the power. I'm pretty sure there's a setting to turn it off, but since I haven't used the music player on my 505, I don't know where it is.
A reset should turn off the player if it is running, and won't do your reader any harm if you decide to do that.
Hope this helps!
dordale
