Hi, I have a late 2012 Mac Mini that I put a 128gb ssd in to mac a fusion drive with the stock 1TB platter drive. To make a long story short, it has worked fine for years, then the SSD started failing causing problems. I took out the bad ssd, replaced it with a 500gb ssd, and left the 1TB drive in, not creating a fusion drive this time. Everything works great, runs just fine, but the back cover won't go back on. I have lines up the white dots, turned it to the black dot, and it just spins and falls off. Anyone have any thoughts on what I am doing wrong or might have broken? I came off fine, just won't go back on. Thanks for any tips.