Well none of the numbers so far repeat and there are 4 left, so it could be a combination of 2,3,9,0?
Trying those combos now.
In order to get the four digits solved, we need to work together. People should post combinations they used, or maybe even break off groups of numbers. I think randomly guessing will get us no where.
Also here are some other discussions on it, if someone with time wants to easily coordinate a larger cracking effort and wants to eliminate codes that don't work.
http://www.gamefaqs.com/boards/672472-injustice-gods-among-us/65442380
http://testyourmight.com/threads/noob-com-seemingly-dropping-more-clues-on-injustice.27846
Here's an idea, someone setup a public Google Docs spreadsheet with all the possible 4 digit codes and people work through them to eliminate them one by one to find the solution.
I just joined TYM and I'm trying some 4-digit combinations also.
Team effort people.
EDIT:
Looks like InjusticeHub revealed 8319 as a blank page result after being a d!ck and trolling around. :The_Villagers:
So have we determined that 8319 is the number but Boon hasn't posted a screenshot yet?
RT @Giru017 @noobde 43 (and growing) strong on google docs trying hard to crack the 4 number. EB: Thou shalt not team up!