Use this guide to replace a worn-out battery on your Evo 4G.
Gently insert an iPod opening tool between the rear panel and the inner rear frame near the headphone jack.
Use your iPod opening tool to pry up the rear case around the perimeter of the Evo.
Lift the rear panel off of the inner rear frame.
Using the tip of your finger, lift the battery from the end closest to the camera.
Remove the battery from the rear inner frame.