Sorry I’m so late to the party, but I just picked up a 2012 Mac Mini to replace my HEIC-incompatible 2009 Mini. Upon reassembly, I also had some trouble reinstalling the antenna plate, and this page came up first in the Google. Unfortunately, none of the replies described the cause. Finding the cause led to an easy solution. The cause is that the ridge of the antenna plate has a thin grove into which which the edge of the case must fit. Left to its own devices, the case edge will slip into one side of the groove or the other, but the opposite side of the plate will droop and misalign the case to the top edge of the groove. This allows the screw hole on the good side to align, but the hole on the opposite side is off by ~1-2mm. The easy fix is to insert the tip of your spudger into one of the holes on the misaligned side to lift the plate slightly. With a slight push on the plate, the case edge immediately falls into the groove, and both screw holes will align perfectly. Cheers!

I just installed a 6 Gbps SATA III Sandisk SSD Plus in my late 2009 Mac Mini (running El Capitan) and was dismayed to find it operating at a negotiated link speed of 1.5 Gbps. I found a discussion thread from 2012 on the Sandisk Forums isolating the issue to a finicky NVidia MCP79 SATA chipset on Macs of that era and suggesting going with other drive manufacturers; I also found that Sandisk had acknowledged the problem and had released a firmware patch specifically for drives in Macs with the MCP79 chipset, albeit only for the Sandisk Extreme SSD. I figured I'd try the patch on the SSD Plus anyway (and return it to Amazon if it failed), so I burned the ISO to CD and tried to boot it off my external USB Panasonic DVD burner (the internal Superdrive has been dead for years). Unfortunately, the Linux system failed during bootup, so I rebooted to the SSD. To my surprise, I found the link operating at 3 Gbps. I had no illusions that the failed firmware loader had miraculously updated the firmware, but I found...