hmmm..it is possible that you purchased a water damaged device. The sticker that I had you look for is a liquid damage indicator...if there is no liquid intrusion, the sticker would be white. Moisture turns it red. No sticker at all may indicate that it was removed, and there was probably a reason for that.
1st Step in Troubleshooting: Do you have a BlackBerry Data Plan?
2nd Step in Troubleshooting: Pull the Battery.