If the red part of the battery image flashes three times and then the screen goes blank, it means the iPhone is not '''receiving power to charge'''. Have you measured the output of your wall charger? It might be that your wall charger is not working. also your need to take a look at the cable is it working. did you clean the connector on the phone? Make sure it is clean and free of debris. If all of those are working I would go ahead and replace the battery in the iPhone. It might have the voltage but not the amperage to power your phone. These are just my 2 cents but I hope this helps a little. Good Luck.