Either you bought the wrong USB board when you replaced it (there are 3 revisions, use a revision different to the one already in the phone, and you don't fix the problem), or there's something else wrong hardware-wise, more than likely a component or two on the motherboard.
It might also be as simple as the battery, try another if you haven't already.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Most retarded thread on XDA in 2013