The most likely cause in this incidence is that the phone is dead. This happens when apps may be too power consuming or the phone does not have a powerful enough cpu to run the app. This makes the phone overheat and as a result fry the motherboard, leaving it unusable. No matter what you do (changing the battery, using different chargers) the phone will not turn on. Unfortunately for your case you will have to buy a new phone.
Hope this made it a bit clearer,
Nathan