How can i fix my crazy trials fruit machine mux missing?

I have currently bought a take it or leave it crazy trials fruit machine it was working perfect till my partner changed a bulb on the lid of the machine it is now showing a unit 1 mux unit missing 30-51 i do understand the code its either a faulty board or a faulty wire or anything like that i am just wondering if anyone has any ways i could find the problem or to anything to suggest it could be
thank you in advance