Take a front facing photo with all of the lights on and clearly individually visible (or in this case, you might be ok with them off like the above, if you are close enough that you can see how many pixels there are in each row, the posted photo is too far to the side for a good map), then upload the photo, and click on the spots in order, and it’ll make a map. You can adjust manually (or by re-editing it in the tool) afterward, if you goof it slightly.
For irregular layouts, this is the best approach. Doing a ‘math-y’ approach will not be easy or adjustable as nicely as this will be.