Why is my mini only showing 6 gigs of storage available?

I just purchased a mini for repair off ebay. It work flawlessly except for a couple of things: cracked screen lower right hand corner and it is only registering as 6 gigs available memory. I have the screen fix figured out (thanks ifixit!) and now i'm trying to solution the gig missing problem. Any thoughts?

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0