1. The phone will not boot unless it's plugged in (either through USB or the wall charger) as once it hits the Sony logo (or animation) it will turn off.
2. Once I manage to get in, I'm able to use the phone with no issues
3. ..and when I unplug the phone again, if I leave it alone, I'm able to do basic things like use the unlock screen go to different homepages, and open the app drawer
4. If I select a widget, app, or go into settings, the phone turns off.
Since an update wasn't available via the PCC or SUS, I flashed the most recent firmware 10.3.1.A.0.244 myself, and it doesn't seem to help the issue so I'm led to believe it's a problem with the hardware itself - maybe a sensor or something that reads the battery as dead?
Does anyone have any ideas as to what else I can try doing, or am I SOL and need to send it to Sony repair (and potentially have to pay to fix it)? Any help or input would be greatly appreciated