I do not understand how går means possible here. Is it an alternate meaning?
Yes. That's one of the meanings of gå. It's quite handy once you get used to it.
Går det att laga? = Is it possible to fix [it]?
Nej, det går inte = No, that's not possible.
Ha, I had no idea! I guess in english that has some remnants in sayings like Anything goes.... Thank you...