Take all the paint out of the gun. Make sure its in eyes off mode. try to fire the gun. It should work. Then make sure its in vision mode. If it will still shoot (with nothing in the gun) then theres a problem in the vision system.
If there is nothing in the gun blocking the eyes (grease, paint, dirt) and if you replaced the eyes either you did something wrong in the process or the eyes are not the problem and the board is the problem.
As for detents you should feel something protruding just ahead of the chamber, it should also recess when you push on it
Lover of All Things Paintball