I have an iPhone 4s running on iOS 8.1.3. I've owned it for about 2-3 years now and have taken good care of it physically and hardware wise. But recently my phone had died. I plugged it in to the charger no problem right? I come back about 20 minutes later to see nothing had changed... I tried adjusting the cord, trying to power down the device, rebooting, safe mode, and just letting it sit without the cord and retrying to charge it. Nothing worked; the phone just kept blinking the red battery logo even of 1 entire day of charging. What is there to do?
There are a few possible things that could have happened. I've ordered them (and their solutions) below from most to least likely.
You have a faulty cord.
It has become frayed on the inside.
One of the metallic connectors is dirty.
Dust or dirt has collected in your charging port.
Your wall outlet is not functioning correctly.
You have a hardware problem.
Your charging port has become disconnected internally.
Your battery is defective.
Many of these cause your device not to charge. Thus, powering on your device does nothing.
Clean out your charging port with a folded index card, toothpick, plastic card, etc.
Call an electrician.
Take your device in to get fixed. (Hopefully, you have a warranty.)