| | Blackberry won't power up or battery image with slash on screen
Had this problem and kept trying charging the battery and/or removing/replacing battery. Sometimes could not use the BB for days at a time.
Finally, in frustration I disassembled the phone. Lo and behold, one of the battery contacts on the circuit board (of the four) was corroded green. Used a cloth to wipe off some (just a little). Tried a pencil eraser and rubbed off more. Finally, I took a push pin and scraped the contact until it was a clean square like the other battery contacts on the board. I wasn't sure how thick the conctacts were, so I used LIGHT pressure when scraping.
Voila ! I now have a working 'berry !