1990 GX81 Mark II radio removal

[sam.]

I have a stock Mark II GX81 from 1990 with AEPQK frame, i was trying to remove the stock radio and replace with another one, there was however one problem, after removing the face plate of the radio, i broke some sort of wire and now all the buttons next to my hazard light button do not work . Can some one please tell me how to remove the stock radio and how to fit in a new one?? thnx in advance