Help Phone goes AWOL

[DroidRick]

I don't know if my phone is starting to suffer old age, or something else. The battery still holds a charge. A few times I have had my phone plugged into my desktop's USB port charging for quite a number of hours and when I go to turn it on it doesn't respond. The screen won't turn on, it won't respond to anything. I must resort to pulling the battery and then pressing the ON button. I just did it now (pulled battery) and it powered up with a message to recharge soon. This is with no apps running, WiFi off and plane mode on. Any ideas what the problem is? It's the original battery.