Your motherboard may be faulty if the phone won't power on after the battery replacement.
Remove the Torx head screws, using a Torx driver, from the 4.9 mm screw holes on the camera plate at the back of the phone.
Remove Torx head screws (3.65 mm) at the bottom of the phone.
Insert a paper clip or similar tool into the small hole on the side of the phone.
Use the Spudger to pry the backplate away from the phone, working along their joint.
Careful not to damage components, gently pry the backplate loose.
Hold the item firmly and peel away the protective film by hand.
Disconnect the orange battery ribbon cable using a spudger, working carefully to avoid damage.
Use a fingernail or spudger to pry the battery upwards.
Remove the 3.15mm Phillips Head #000 screws from the motherboard.
Disconnect the rear-camera connector carefully.
Remove the plastic edge bracket at the top of the device.
Disconnect the antenna from the bottom piece of the screen plate.
Lift the motherboard off the frame with gentle care.
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