Is this a logic board problem? New dock connector unit makes microphone not work.

So i have some water damage on my original dock connector. That means the volume rocker has not worked and no sound outputs on my phone unless I plug it into its charger and then remove it. If I sleep the phone, the sound disappears again.

So I figured I needed to replace the dock connector. Bought a unit for the 4S, had someone install it, and it solved the problem. Volume worked normally, battery wasn't draining anymore thinking it was docked in, but the microphone failed. I can't make phone calls because no one can hear me.

The guy tried an OEM 4S dock connector today, still same problem. He said it may be a motherboard issue. What do you guys think the problem is? When he put my original damaged dock connector back, the mic works again, but the volume/docking problem returns.

It sounds like possible water damage to the logic board - probably seeped through from the dock connector. Take it to Apple and swap it out for a refurbished iPhone 4S which will probably cost you some $$. Make sure you get an estimate first. Apple does not repair iPhones, they swap them out for a refurbished one at your cost.