are you aware that the trainer transmitter must be in the off position also.
have you been in contact with the club instructor yet for him to check it out ?
it sounds that dad is just as inexperienced as the student and knows just enough to get into trouble trying to fix a non existing problem since he only assumes this is how it should work.yes that statement of "loosing the link" is suspicous!
the hobby shop where you got it can help also !
tom