Samsung Galaxy s4 mini does not turn on? Computer does not recognize.

My samsung galaxy s4 mini just suddenly died at work (it had over 50% of the battery charge left).

I removed the battery and inserted it back on and tried to turn the phone on, but it does not make the wake up sound nor does it vibrate.

I also tried to connect it to a pc and it failed to recognize the device.

I am guessing it could be either that the usb port is faulty or that the phones motherboard died?

So I am looking for a solution on how to fix the phone if possible.

Thanks for helping me out and sorry for my english.