For Z1 C6903, it may seem that the steps are applicable, but with a slight twist: After removing the cover, you need to use T4 screwdriver and remove the screws holding another "layer" (black plastic). I have to use the guitar pick and remove the black plastic "cover". Then only you can remove the battery (the C6903 battery has plastic frame with screw holes (x 4). Other than this, steps above are applicable, but I can't get the adhesive material to align properly. Remember not to dump the phone into water.