iPhone 5 not charging or connecting to iTunes

So, i bought an iPhone 5 last week, the seller told me everything was working except the logic board. When i got it i did a soft reset and it booted up, it showed 10% battery. After the battery drained i tried to plug it to my computer and no response. Same with wall adapter. I replaced the dock connector and the battery and still no response. The phone boots up and functions perfectly but doesn't recognizes the lighting cable or any kind of power inlet. Any ideas what could be causing the problem? (I've heard something about the USB Power IC, but not sure about that). Thank you in advance!