So I see that I have 90% of my battery life, I try to download an App and the phone resets itself and now I have 3%. This is happeneing eveytime! What could be the problem.
Most likely you need a new battery. When my OEM battery started to go bad, the phone would show a near full charge, but after a minute or so of using the internet or making a call it would be in the red and reboot. When it came back on after the reboot there would be only a few % left and it would then reboot loop until it was completely drained. New battery and no more issues.
The OEM battery was a little over a year old.