The phone turned off while my son was playing a game on my Lumia 920. I tried to charge it, but it did not charge—and it's not even showing Nokia Logo. It shows nothing—just like a dead phone. I tried both hard and soft resets, but nothing works.

I thought it was the charging port because there was a small physical defect near the USB charging port (voiding the warranty). I ordered an OEM USB port charging connector flex cable. I changed the charging port.

Now I see that it installed the driver on my PC when I connected through the USB cable. But it's still not charging, and it displays nothing when I try to charge it or power it on.

What can cause this problem, and which part needs to be changed in order to work properly? Thanks.