On my phone also at the moment. Didn't think you were short, although it's understandable if people are. Appreciate everyone's perseverance.

Ok, this is now getting proper readings.

They both measure around the 19V mark.

Excellent!

Now is the time to sort the pin issue.  Hopefully, you can now get a good volts reading at the '12 volt' pin on the display connector.(blue wire)

I'd still be inclined to stick with the instructions that came with the display as far as pin 1 vs pin 4.

Once you test the blue wire, reconnect the display and cross your fingers.

Hopefully that brand new display will spring to life.