The Safe kinda works, just played it, but I'm not sure if you make a mistake it will resets. because at some point I made a mistake and the code didn't work anymore. so if you fill in the code good in one try it should open. this definitely will be fixed after the game jam is over :)
You're right, the user feedback only got added in the next build but at that time we couldn't submit it anymore. Try inputting the right code from the get go, without inputting a single wrong digit, and you should be good. Thanks for playing! :)