Most of the times the “No medium found” error means that the your SSD is damaged. Please disconnect external power supply and take out this (there used) SSD and reconnect it properly (if compatible with Librem 14 at all). Or even better, test it within some external housing device at the first place. Did you ever have had some data on it?
P.S. Just leave SD card thoughts aside, at least for now. Nothing hidden there (if SD card inserted sudo fdisk -l will show it). Similarly if your SSD (that otherwise works outside), or inserted SD card, is not getting enough power you might have internal Librem 14 issue. Please check:
etc. as within this linked post. Are you installing there some Linux distribution?