16x2 LCD with Leonardo via "LCM1602" - no characters

ubermick:
Anyways, got it going, but still no luck. The guesser goes through the eight attempts, but none of them did the job. Best I got was the first attempt (which is the default), which at least left the LCD on, but just gave me the same 16x2 array of blocked out characters.

That actually looks like it might be working.
Try adjusting the contrast pot. Turn it until the pixels start to go off to see if it is just
an adjustment problem.

One thing though, when I tried ohming out everything, to see if I mucked up my soldering I did notice that I was getting a reading on all pins, as if everything were through a 10k resistor. So unless this is common practice for these boards, I've either got a faulty one or a short in my soldering (which would surprise me, since while my coding skills are beginner, I'm competent enough with a soldering iron…)

Not sure what you mean by that.
There are no 10k resisters.
What were you measuring?

It is hard to tell from the photo but it looks like the solder isn't fully melted into the holes.
You shouldn't see any gaps around the pin inside the hole.

Can you show a a closer clear photo of the soldering so we can take a look.
Also, it might be helpful to see the back side so we can see the actual backpack.

--- bill