Hello, I have an XPS 15 9550 with 256GB SSD. I bought an interposer cable with rubbers and tried to install a 500GB Samsung 850 EVO HDD in the spare slot. Not showing up in disk management,  not in device manager, not even showing up in BIOS. SATA0 and SATA1 are turned on in BIOS. I double checked the interposer connections and everything seems tight on both ends. This should just require partitioning to work, right? So I could just have a DOA 850 EVO. What else could it be? BIOS is set to RAID not AHCI, but that should be OK?

Thank you all