iPhone says its charging, but is not.

My iPhone 4 started having a hard time charging. I was told that I needed to replace the dock connector and or the battery, so I went ahead and did both(kill two birds with one stone). I got the iPhone back and it still would not charge! I was told that the entire logicboard is bad if it wont charge after the new battery and dock connector was installed, is that true? The iPhone show the little lightning bolt symbol with the battery, but discharges the phone rather than charging it. Any ideas on what it could be.? A bad connection? Bad cable? Bad logicboard? Please help?!!