I have a 3 yr old Droid Mini that recently started shutting down on it's own. I had purchased an after-market battery last summer. I also had a virus scare, in which I immediately shut down, then ended up doing a factory reset on it. It even shuts down in Safe Mode. As for the battery, it says that it is fully charged, but then when I go to use it, it soon shuts down. How can I tell if it is truly a battery issue, vs bad software, causing me to have to purchase another phone?