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If normal diagnostics have not helped (e.g., batt-pull reboot, WIPE, reload OS, etc.), then you indeed need to seek warranty support. You seek that from your original place of purchase, your mobile service provider, or an authorized service center...the method varies by region. When you purchased your device, you should have received documentation detailing your warranty coverage along with methods of using it.
Occam's Razor nearly always applies when troubleshooting technology issues!
If anyone has been helpful to you, please show your appreciation by clicking the button inside of their post. Please click here and read, along with the threads to which it links, for helpful information to guide you as you proceed. I always recommend that you treat your BlackBerry like any other computing device, including using a regular backup schedule...click here for an article with instructions.