Chosen Solution

I have a series of 4 led strings (capable of up to 41 strings connected to one). These exact lights: https://www.homedepot.com/p/Home-Accents… See a picture for a diagram of the wiring. But here is my best explanation: I run one full-length string one on guttersI needed more, so I added the 2nd to complete the top and trimmed it to fit the required light areaI connected this to a 6ft. extension cordthe 6ft cord has 2 separate extension cord that runs off it.22’ extension cord to the 3rd light string in the connected series around windows #141ft. Extension cord to the 4th light string around window #2.All lights work except string #2 in the series….String numbers 2, 3, 4 are all trimmed to the needed length, and String #2 is greater than 20 bulbs.Lights work on all strings EXCEPT #2… I tried swapping the led bulb in the single socket to test since it cant be the fuse or light strings #3, and #4 would not work correct? And nothing happens when testing different led bulbs, not quick burn out, or even a little bit of light. I am so confused… EDIT - sorry I forgot the pictures! - hopefully, these annotated ones will be more helpful anyways? Thank you all for the help!

The 2nd bulb may be burned out, you’ll have to buy a new bulb.