This is why I have asked if anything was removed from the Original Build up.I would consider taking them out and putting in different ones but I don't think that is the issue. Maybe a trace is damaged somewhere?
This is crucial as not knowing the quality of the board, any removal of any part in the original building of the Board could have damaged a trace.
This is why temol suggested the audio probe. this will tell you from the In to the Out highlighted in RED on the Schematic he supplied where the audio stops along the way is an Issue.
You listed C4, Is that still an Issue?
Q1 Drain is ??????????????
If so, Reflow it & Test again!