I saw in another thread on this topic that the problem is caused by people not properly exiting their sqlmap shells, for some reason it causes the box to lock up. I did manage to get through it myself the other day, after giving up and coming back later several times - I think it’s mostly luck and/or time of day.
My biggest gripe with this box was the FTP access - is there any way to find the FTP credentials other than reading the walk through? I wasted hours trying to brute force it before I gave up and checked the tutorial - the creds are right there but there’s no indication given that they can be acquired any other way… seems a bit cheap if you ask me.