As I understand it (based on information posted by knc1), when overly discharged (or with damaged firmware), the kindles default to the "20 hour charging curve" when connected to a wall charger. You may need to trickle charge the battery for a full day. And with a bricked kindle, it is possible to discharge the battery enough to damage it, causing it to become a much smaller usable capacity battery. A damaged battery may not be able to hold enough charge to flash the main partition image in one session.
Last edited by geekmaster; 12-11-2012 at 11:56 PM.