Successfully replaced PRS-500 battery
Thanks to all for posting this info. I just finished replacing my battery with the one from smavtronics.com. Only problem I ran into was that one of the tiny screws holding on the plastic side bezels seemed to be glued in and I stripped it badly. Dumb mistake. Finally found a combination of screwdrivers to get the screw out. It was up near the SD card slot and all the work on it weakened the plastic and the top part snapped off. No big deal though. I'll probably just glue it on. Hopefully I'll get more battery life out of this new battery. I'll report back if there are any issues with that. Thanks again for all the info.