Gear box problem

Hi, I have trouble with the gear box. I bought the car a year and half ago but just drive it one day. Only after I travel with it for seven hundred miles it show a yellow sign in the dashboard yellow sign similar to the setting one in the phone saying in French ( vous pouvez roulez mes avec restriction). Arriving home I stop the car in the morning I drive it around two miles and the car stopped it self. I do not want to star again leave it for around two hours and turn it on and drive it for two miles and it happen again the car stopped it self. I bring it to a mechanic guys tell me to buy a ( capteur and block for gear box ) did not work and the car now does not turn on. If I try it there is no answer now. I am wondering if I buy a complete gear box brand new it going to work I hear this is a default on all Q5.