Answer to: iPhone wont charge but will turn on when plugged in.It is usually the battery connector not completely attached
Answer to: Replaced battery, do I need to use untill 0% charge etc,etc?Batteries no longer need to be drained or completely charged. The batteries function best when kept between 20 and 80%. The only thing 0% and 100% do is help keep more accurate record of where battery is
Answer to: Why wont my iPhone 4s turn on?Sounds like the battery connector is loose. Remove back and then disconnect and reconnect the battery.