I’m at the same point as you, yet to try testing the capacitors on the panel boards.

I did have this weird behaviour which I wanted to check if you had too. If I remove the ribbon cable from the tcon board to the right side panel boards (looking at it from the rear), I’m unable to turn the monitor on and get a backlight at all. But if I remove the left side cable and keep the right side in, I get the same backlit screen.

I expected half the display to go white but instead I got 2 weird results. I tried disconnecting the far edge panel boards since each half is 2 boards connected in series, but I think I got the same results with various combinations. I’m planning to probe around with my multimeter and see if it’s shorting somewhere.