I was reading yesterday when this popped up (I was trying to rush through on a low battery, my fault), so I plugged it in. I noticed the light didn't come on, so I unplugged and re-plugged and after a few seconds the yellow charge light finally lit.
I checked on it a short while later to see if there was enough charge to finish the book ( ) but it still had the same critical battery page up. Tried to turn it off to see if it would go away, didn't work. Light was off and now I can't get it to come back on. It won't charge and won't turn off, even held the power button for 30 seconds and no change.
Also, I've had a few instances where a page 'freezes' and I can't turn it or do anything until I power off and boot up again. Then when I go to 'reading now' it sends me to the wrong page.