Menu button does not work

[Balazs]

Hello I need some advice.
My menu button (d8) does not work on my sttng pinball.
There was a battery leakage on the mpu What I did so far: bad traces repaired, I changed u16, u17, u20, changed bad resistors, checked continuites according to the continuites schedule, (attached photo)
D14 diode according to the multimeter is ok.
Problem what I found is before the r78 resistor the voltage is 12v after the resistor is 5.4v (should be 12v)
What should I check next?
I attached the drawings for the circuit.
Thanks
Baz

 

[DRD]

Sorry if obvious but has the actual menu button failed ? These things are quite fragile internally and do break down over time

 

[mufcmufc]

Short it with a screwdriver (the pins on that button at the door) if it works change the button

 

[Balazs]

Short it with a screwdriver (the pins on that button at the door) if it works change the button

I sort it on the j205

Short it with a screwdriver (the pins on that button at the door) if it works change the button

The button is ok.
I shorted those pins on the j205 and nothing happened so the problem on the mpu board.