i was measuring against the right side/analog. actually when you said that it is a GND pour i got really worried its not connected to anything except pin3 of ic3 and the connecting jumper pin.
What I meant to say was: the “gnd pour” on the bottom side, analog section (right hand on your pics), shouldn’t have connection to ANYTHING, i.e. including GND, it’s just there for a little shielding but has no function. But if you damaged the solder mask laquer and made connection to it on more than one occasion, it could be responsible for a short, too.
Anyway, maybe try to resolder a few things and carefully inspect the whole area around the jumpers and IC3 under a good light and maybe a magnifying glass. Keep trying to solve that problem with removed jumper and IC3. If you can’t find anything, you could try removing the IC socket or the jumper headers, although desoldering on double sided PCBs is never easy and your J3 doesn’t exactly make you look like an expert in that field ;). A way to check at least one place from above without risking to damage the PCB is to remove only the black plastic from the jumper headers. Normally you can move that plastic if you’re patient and maybe heat up the pins a little.
S
