My Samsung S5 don't charge and I can't turn it on.What should I do?

[AC Question]

Last night while using my phone,the back key on the down right part suddenly stopped. It doesnt light up anymore unlike the other one, then it works on its own. The battery charge drained faster than usual, my phone shut down and it dont charge no matter what i do. This morning I tried turning it on expecting that it will, but it didnt. I tried charging it again using a different charger, I expected that it charged. I let it rest till this afternoon, I tried turning it on again, it will vibrate many times then the blue light on the upper left lights up and the two light up keys beside the home button lights up too but that's it! it never continued to turn on. I tried the hard reset but still, it didnt work. Everytime I try to turn it on, it will just vibrate no lights. What should I do about this matter?