i have an o5 kfx and all my lights and the electric start button quit working and so i checked and cleaned all the wiring connections and nothing works could my cdi be bad

 

No it sounds like your battery is dead......

Generally the CDI box going bad has nothing to do with your lights....CDI is your ignition (not the one you put the key in) and if the CDI is bad your lights should still work the quad will just not run right, or it won't start. But the lights and start button should still work.