Boot the laptop while pressing on the :
for 20 seconds.
This will boot into recovery mode
go to Disk utility, stand on the Macintosh disk and go to File/Image->Create Image from-> Folder->choose the Macintosh folder.
Make sure to de-encrypt or to mount(In disk utility) the HD first.
let the process finish
This Will only copy the files, not the disk
That's it!