My phone was at 1%, so I put it on the charger. A few minutes later, I go to check my phone, and push the home button. Nothing happens, so I push it again before taking it off the charger. Once it's off the charger, I pressed the power button and the Apple logo screen appeared, and the phone started to turn on. It's on now, and seems to be working fine. However, why would my iPhone die while on the charger? It's an iPhone 5S and I've had it a little over two years.. Is this a sign that the battery or the phone will need to be replaced eventually?