Problems with a Screen that used to work

[Ekisu]

I'm using a screen from an old mintek dvd player on my portable. It has an AV in port that i was routing the n64 signals to. Everytime i turned on the system i would have to select external input to get the n64 video to show up, but one day the button that i used to select the input stopped working. Is there anyway i can get around this so i can still stream the video to the dvd player's screen. When it turns on now it just shows the dvd player display screen and says no disc. I've tried fixing the button but the traces lead into the central IC.