I decided to purchase a BLTouch for my Ender 3 V2. I did all the physical installation of the BLTouch at the same time as adding LED lighting. I plugged in the power to test the lighting (BLTouch was not plugged in yet) and everything came on fine and the lights worked as expected. I plugged in the BLTouch, hot-glued it in place, and finished zip-tying and screwing in everything else back in place.
I connected power once again and powered on my printer. The fans came on, the new lights powered on, but the display didn't come on. I turned it off and back on, still no display. Then I smelled the distinct odor. I quickly powered off the printer and opened it up to look at the mainboard. I couldn't see any major scorch marks at first, so I decided to power it up again. That's when I saw the small spark and magic smoke at F2 in the picture below.
I feared the worst that I had fried my mainboard, but thought maybe it was the BLTouch. So, I unplugged the BLTouch and powered the printer on and miracle of miracles it powered on. All the fans, lights and display were on.
So something with the BLTouch is causing the short but I don't know what it is. YouTube videos that I watched for installation showed a different cable than the one that came with the BLTouch that I purchased. My BLTouch came with a 1 meter extension that is actually 2 sets of cables. One set is a pair of black and white wires that I deduced were for power. The other cable is a set of three wires colored orange, red, and brown. I zip-tied the two connectors together to make sure they stay together. On the BLTouch end, the orange and black wires are next to each other. The connector in the bottom picture is in the same orientation that I plugged it in.