there is a break / bad connection somewhere between the cpu board ( IJ4 pin 2, white wire) and the white wire on the door switches. the diagnostic switches use a ground as a common that is why it is working when you short the wire with the screw driver to the metal.

start by checking the wires at the memory protect switch one will loop in and out (it should be white, this is the common for the diagnostic switches also.) and the wiring at the front door connector

if you still cant find the fault there, there are a total of 4 connections between the cpu board and the diagnostic switches for the common wire, the first is at IJ4 (pin 2), the second where the back box wiring connects to the playfield cabinet wiring (pin 4) and the third where the door wiring connects to the cabinet wiring (pin 13) and the 4th is the spade terminal that connects to the memory protect switch, from there it goes to the diagnostic switches.