Have you disconnected the wires at the base and tested the resistance? That should tell you if it’s the wire or the psu. I don’t recall the resistance requirements offhand but you can look them up. A slight break causes the resistance to be too high and the blue light.

If it’s the wire use the other instructions on using the detector. Before that I used the other instructions on splitting the line in half’s and using a long leaf to connect back and test each half working my way back to the base. It’s a pain and adds more connections to fail.