One thought on the problem you had with charging it, I have a PRS-505, and took it into work to charge via my work laptop (previously I charged on my own laptop). I was thinking I like to read in bed, and a various times in evening, so use the down time at work to get a full charge.
Anyhoo -- The work laptop is a dinosaur, so I plugged it in, saw error msgs (normal for plugging a usb in at work), and noticed a yellow light on....three hours later I try it, and it keeps shutting off as soon as I try it.
Basically, since the usb connection wasn't set up correctly, it kept the reader running (trying to access?) so the yellow indicator, but did not charge it, and drained it instead.
Later when I rebooted, the reader connected properly and charged great. (strange, since my Archos or USB drives do not work on this laptop's usb).
Don't know if this is another piece of the puzzle of your charging problem, but thought I'd share.