The spotmeter F buttons are standard membrane style buttons (like on a game controller). Its common with game pads for the membranes to get out of position, for the conductive ink to become dirty, for pcbs to crack, and or for posts to break.
If it were me I’d open the meter (video online does not make this look hard), and simply inspect and clean the membranes and the pads on the pcb, reassemble and see if that does the trick.
Not being able to take a reading makes me think of how the meter behaves when it’s still in set ISO mode. Just double checking that you’re able to move it between ISO and Time modes as the meter will not take readings while in ISO setting mode.