Once the back case is removed, locate the battery. It is the large brick embedded in the phone. It has BLU Products, a caution statement, and a barcode on it.
Insert your finger into the notch near the lower left of the battery, apply pressure and lift up.
Use the Spudger to pop the inner back casing off. Do this by lightly raising the side of the battery housing, then sliding the Spudger around the case.