Also I would like to add, that 9/10 the solution is very simple. Remove the two dock screws and it generally works. Unless you dropped in water or something stupid like that.
I replace and repair items for a living, and I came across this when our first unit with dock problems came in.
I believe it is a manufacturers defect that causes the problem, someone can correct me if I'm wrong, but for whatever reason, removing those two screws that hold the dock connector in place generally solve the problem.
I joined this community to help and now I think genuinely I found an answer that will help a lot of people out.