I have no clue what to do all other buttons and joystick direction work.
This thing got a mind of its own . I have no idea what to do
Double check your wiring for a loose connection. Do you have an ohm meter? If yes put that on that button and test it to see if its intermittent. Have a really good look at the joystick to see if something is or has moved out of place.
Sometimes the spade connectors can be a little loose, but a gentle squeeze with a pair of pliers can often tighten them enough to give a secure connection. Like @alphanumeric says, check all of the wires for the joystick, both at the joystick end and the Picade PCB screw terminals.
i manged to fix it by just fiddling with each connector thanks for the reply both of you !