After removing the back case, the battery is the next obstacle. Removing the battery is the solution to a lot of problems because it essentially restarts the phone. It is the gateway into the rest of the phone. The battery is a simple obstacle to overcome.
Turn the phone over so the back side is facing you.
Placing your thumb on the bottom of the phone, apply pressure to the small ridge in the middle of the phone and push upward towards the camera.
The back casing should slide off.
Using your index finger, pull the top of the battery out first. Place your finger at the top center of the battery in the gap that is provided. Then pull the battery towards yourself.
The battery should easily fall out after the top of the battery has been pulled out.