My s5 goes randomly off and now completly off . Cant switch on it now at all and when

My s5 goes randomly off and now completly off . Cant switch on it now at all and when i try to charge the phone it shows cant charge and i dont know what to do and plss do help me
* my phone galaxy s5 goes off randomly
* a tap on the phone it goes off
* now it is not charging at all and is off
I gave it for service and they out in a new boot file and it worked for some Tim me quite well and again the problem started
Someone please do help me with it:confused: