Dell inspiron 5520 not charging


Nov 15, 2011
i brought my brand new laptop i5 2 weeks ago and it was working perfectly! today it was charging normally and then suddenly the yellow LED on ac adapter turned off! after that the laptop is not starting! the ac adaptor shows yellow light when it is not connected to the laptop but when i connect it to my laptop then it goes off! i hav tried removing the battery and booting with ac adaptor but same problem!
i tried different sockets but same problem.. i tried asking ppl on other forms and they said that the main board needs to be replaced.. i am under warranty but y did this happen on a new laptop? :( is my main board really at fault here?
thnkz for yr help guys..