When did they work? Prior to getting approved in humans they were killing animals at a high rate. To the point where animals were smashing their heads against shit to get the chip out.
Additional veterinary reports show the condition of a female monkey called “Animal 15” during the months leading up to her death in March 2019. Days after her implant surgery, she began to press her head against the floor for no apparent reason; a symptom of pain or infection, the records say. Staff observed that though she was uncomfortable, picking and pulling at her implant until it bled, she would often lie at the foot of her cage and spend time holding hands with her roommate.
I understand testing on animals is tough but this was straight cruelty.
https://www.wired.com/story/elon-musk-pcrm-neuralink-monkey-deaths/