For everyone wondering, it was that I indeed had the wires backwards. Black to positive, white to negative and all is well again. We take the battery completely off in wintertime and keep it in our basement. Even though I try to leave the wires on their respective sides, I suspect that when it was moved in and out of the shed they shifted and I didn’t think about it until I had no power. I’m still trying to figure out which one is supposed to have the inline fuse though, as it’s a red wire. I’m assuming positive. I want to make tags to identify them right on the wires.