iphone 4s died at 100%, wont turn on or charge even though it was charged.

I have been having problems with my iphone turning off at anywhere from 80-100%, in fact I haven't seen it anywhere near 50%or less in about 2-3 months. Sometimes it would turn back on if I press the power button or home and power button, and would show the same battery % as when it shut off, but would die right away again till I charged it. Sometimes it wouldn't come back on till I put it on the charger. Last night I took it off the charger when it was 100% and went to use an app right awayand it died still at 100%. I put it right back on the charger and expected it to turn right back on or at least turn on in 15-20 min. It has been on the charger sonce last night and still has not come back on, and yes it shows the lightning bolt like it does whenever it is charging, and shows no battery power. I have tried pressing the power button both on and off the charger, tried pressing the home and power button for 15 seconds, and even tried longer both off and on the charger, I have tried changing cords and the adapter, and different outlets, I have tried plugging it into the computer and it again shows the lightning bolt and low battery thing and itunes and the computer doesn't even acknowledge that it is plugged in. I'm confused as to what else I can try. Of course it dies after 1 year warranty is over.