When you completed the soldering, after that you have to using the Ohm range of Multimeter to measuring the wires on the soldering tin of two points, because maybe the wire has a layer of dielectric on the surface.
Sometimes we will scraping with a knife for the kinds of wires where wish to solder.
Can you make a drawing or schematic of how the wires are connected. The pictures are unclear to me. Include ALL wires (for example, where do the red/black wires at the top of the picture go?). Also the black cable, on the bottom right, how many wires come out of it and where do they connect to/come from? If you don't have schematic software, use Paint or sketch it out on paper and take a picture.
I don't see a blue wire in your pictures. I think I see which wire from the cable is red. Where do the red and black wires at the top of the picture go. Can't you sketch the connections?