A couple of things to try. First you need to be using an original BB PB charger, it has a higher output than even a BB phone charger. If you look at the battery icon and see what looks like a lightning bolt across the battery it's charging. Leave it this way for up to 10 hours and sees if it charges up. If you're not using a PB charger you need to get one or another charger that when plugged into the PB turns on the lightning bolt icon. If the icon is only a plug icon it will never charge the PB fully. With it plugged in you can try a restart after it's been plugged in for overnight which will reset the battery icon if it's messed up but don't do this unless you have it plugged in and it shows the lightning bolt.
