Testing for bad ws2812b?

I bought a 100 pack of ws2812b SMDs last year (product link) and wired most of the together for a string of christmas lights for a tree. It was more work, but way cheaper (at the time) than buying a strip.

I had a few left over that I kept stored away until tonight when I decided to work up a little circuit to enhance my wife's Halloween costume. Problem is, I can't get them to light. Initially I had 3 soldered together, making sure that the voltage and data were going in the right direction, but when I plugged them into my uno with a very basic neopixels based sketch, none would light. Figuring I had a bad one, I desoldered them all and tried, one by one, on a breadboard. Still no joy.

I tested and confirmed with a multimeter that I was getting the required voltage from one LED to another and reading voltage on the DIN/DOUT pins, but never any light. If I put the christmas strand from last year on the same pins it works great.

Is there anyway to tell if these are just bad LEDs, or have I missed a step somewhere? I figured if the multimeter showed no voltage on one or more of the pads, that would be an obvious sign to trash it, but since all three show voltage, both when wired together and separately, I can't figure a reason they shouldn't light. Is there more I can do to test?

You have to show us exactly what you did and how you wired it up, not what you think you did, so a photograph along with a schematic seems to be the minimum you should be posting.

Not to sound unappreciative for any help I get, but how would a photo help here? I can take a picture of the LED, but it just looks like every other LED shown in the product link. I could take a picture of the multi-meter readout, but I was already pretty specific about the readings I was getting.

As far as hookup, see attached

A photograph of your wiring would permit us to see if it matched you schematic.

This maybe relavant or not.

I made a PCB with lots of WS2812b chips on, several of them became damaged due to overheating the legs during soldering, not sure if it was a bad batch, or me ! But I would suggest using the lowest temperature you can for the minimum amount of time. I found that if I got a duff LED I could short the DI to DO and make the rest of the matrix light, thus proving that it was that LED that had gone down.