This question was just put on hold with the "questions require a goal we can address" reason. I'm not sure I agree with that, because the question has a clearly stated goal in bold:
I feel like I need closure, but the employer is not explaining this test result to me. How should I help myself move on?
We know lots of people coming to this site struggle with being rejected in interviews, and/or struggle with how to interpret what they're told when they are rejected. Questions like this may fall in to a gray area in the strict sense, but I do think there's a lot of potential value in them.
Further, it's a highly upvoted question with many highly upvoted answers that have interesting comments. I feel like it's a bit of a shame to shut it down.
I have voted to reopen and would ask others to as well if they agree.