I bought a 2,5” SSD for my thinkpad e595 and when I've opened it, theres something in the ssd slot. I bought it just with M.2 memory, so I don't know what
How to Install an SSD in Lenovo Thinkpad (T410/T420/T430) - Kingston Technology - YouTube
Lenovo ThinkPad T420s Power Jack Replacement - iFixit Repair Guide