NVME dirive doesn't show up

[belfastraven]

Have you tried ,,  dmesg | grep nvme

If you have nvme-cli installed, and/or smartmontools,  you can run smartctl -a  on the drive or various nvme commands  (e.g. sudo smartctl 
-a   /dev/"your device" or sudo nvme  error-log  /dev/"your device".  to see if the device reported any errors.  The logs seem to be cumulative,  so you should pick up any errors from your emmc boot.