I’m running the HEX file you suggested. There are no shorts to ground as far as I can see. Here are the results I got for each pin with estimated timings but not detecting small changes. Looks like there may be an issue with the first blue pin but that shouldn’t cause the entire display to fail. I’ll post an update when I figure out how the minmax/range features on this multimeter work so I can check the pins aren’t stuck.
R1 - 0-5v every 0.5s
G1 - 0-5v every 0.5s
B1 - 0v
R2 - 0-5v every 1s
G2 - 0-5v every 1s
B2 - 0-5v every 1s
A0 - 2.5v
A1 - 2.5v
A2 - 2.5v
A3 - 2.5v
CK - 5v ish
LT - 0v
OE - 2.5v
EDIT: If I’m using it correctly, the latch pin is sat at 0Hz (nothing at all indicating a pulse), the clock at 1733Hz and output enable at 5200Hz. Multimeter might not have enough resolution to see the latch pulse though.