iPhone 6 Battery Replacement
If possible download Battery Life by Battery Life from app store onto iPhone and note current battery wear on the original battery.
Using a flat plasticx tool, insert under the battery and gently pry up. Do not pry against the motherboard.
Replace bracket over battery and dock flex cables with 2 Phillips screws.
Close iPhone screen onto the body, making sure the screen is properly secured in place.
Screw bottom of iPhone with 2 pentalobe screws, and test iPhone and components.