How do I fix HMD not found error, if it is hardware DOA, what now? DB?

I keep getting error 200 HMD not found. Replaced cable to headset, one of the lighthouses and reinstalled software and reset headset. I get just the solid red light on the headset, "Vive Cosmos" shows up in devices in settings of windows add devices area. How do I know whether to replace daughterboard now, or motherboard of Cosmos Elite headset to further narrow down the issue?