internal SSD crash. macbook retina early 2016. Mac OS X el capitan
If you’re not sure you are doing the full erase correctly, you can follow this guide. It will repartition the drive erasing everything on it and let you attempt a clean os installation. 


https://apple.stackexchange.com/a/354246/5472


If you’re not ready for that, consider installing on to an external drive to back up any files and make sure it’s not something other than the SSD failing or needing to erase everything first.