Galaxy S4 sudden died out topic

Hi, my Galaxy S4 suddenly died out while I was using it halfway. It was still charging (actually 100% already). The phone blackout and I couldnt turn it on.

Here's what I tried:
1) pull out battery and wait for a while then put it back and power on
Result: nothing happens

2) same as 1) but with another spare battery
Result: nothing happens

3) let it charge (to power socket) and waited for about 15 mins
Results: the top side of the phone was warm (beside the microSD slot) and I still cannot power on.

Is this phone useless already?