[Zelandeth]

Now we're getting somewhere.

Having the cards out and reseating the various ICs has rewarded us with a working voltmeter.

The attached screenshot shows one column (right) with a car battery attached to the relevant leads captured using the data hold function, the second column (left) shows it with the leads shorted together. Had to do that as it can detect when they're not connected to anything and just blanks the display for that value out.

Definitely making progress, as this was just showing garbled nonsense before.