Device not charging past red and slow itunes connection

I have two motherboards with slow charging and slow itunes connection. They both dont charge or read the battery past red, and both take about 30 seconds to connect to itunes. Ive tried new hard drives and batteries on both, what options do I have left?

I'd like not to replace the logic board because of its price, if anyone knows what component is broken I could have a go at resoldering it from a donor board.