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My iphone 6 would die quickly after a full charge. I decided to replace the battery myself, so went ahead and bought a replacement battery through ifixit. I followed the instructions on the webpage. It turned on but I turned it off to double check everything is ok now it doesnt want to turn back on. I cant use the old battery because it was dead. Sceen doesnt do anything. This isnt the first time i open an iphone so i know to be extremely careful when opening it. I also changed a battery of another iphone after this one and works perfectly!
Did you make sure not to mix up a long screw for the 5 screw holes for metal plate that goes over the screen cables and connectors? If a longer than usual screw goes into one of the screw holes that are on the motherboard, it can cause damage to the circuit traces on the logic board causing the phone not to turn on. Also check if the phone has booted up by plugging the phone into a computer and checking iTunes.
