If the plane was constantly raising its nose that sounds like your elevator is just out of trim. Was the pilot ever able to get the plane to fly a pass straight and level? Did he try doing any flight trimming? I have had a couple of planes before where I ran out of trim on the elevator and had to land it out of trim. That's not a problem with the airframe, but just a badly missed initial elevator setup. Of course, that doesn't mean you don't have a CG issue or any number of other things, but you really can't know if there is anything else wrong until you get the plane trimmed for hands off straight and level flight.