It sounds like more brown material and a little patience is needed! Afterall, it’s still cool in Minnesota so the process will take longer. But don’t fret… it will happen!
Something that can help speed the decomposition process and re-invigorate the microbial population would be Bokashi or Compost starter. Both will speed the breakdown of your kitchen scraps, as well as increase your microbial population. An actively decomposing microbial population is what creates heat in a compost pile. The more microbes you can add, the better.
If possible, I’d suggest moving the composter to a slightly sunnier spot as well. Extra heat will only help the process. I’ve also attached an article that should help: