My Blackberry Curve 9300 on Mobilicity keeps turning off. Been happening with increasing frequency (now up to 6-7 times) a day.
Basically turns off randomly and accessing data especially seems to trigger it.
Can do a battery pull to power it up for a little while, but will not stay on. Only way that it stays on longer than a few minutes is to power up while plugged in. Really don't think it's a battery issue, as the battery is fine after the random shut and down and reboot.
You should try wiping the device so that it is back to factory settings (i.e. no third party apps) and see if that helps as there could be an offending app. If that doesn't work, you can try upgrading the OS and seeing if that will solve the problem.
If neither of the above work, then it may be faulty hardware.
Take a close look around where the battery "sits" into the back of the phone. Make sure the contacts on the battery are nice and clean they should be gold colored showing no corrosion. Also the battery when sitting in the back of the phone should be snug with no play or movement.
If everything here checks out, and your within the 365 day warranty might as well send it in for service.