Rui Xu, the former COO of the failed YC-backed humanoid startup K-Scale Labs shared candid insights about what went wrong on his blog, in a post titled, “Six Things I Learned Watching a Robotics Startup Die from the Inside.” “I spent a year as COO of a YC-backed robotics startup trying to build affordable humanoid robots. I was forty, had 15 years of hardware experience shipping products at Intel, Xiaomi, Lenovo, Amazon and ByteDance, and joined to run supply chain and product operations. The company didn’t make it. We never closed our Series A. By late 2025, it was over. I’ve written about the good parts before. The hackathons, the garage energy, the first time the robot walked. This time I want to write down what I actually learned. Some of these are industry-wide traps. Some we walked into ourselves.”