Nearly flawless instructions. I replaced the default 5400 RPM 1TB hard disk with a Samsung EVO 850 500GB SSD (2.5” drive style). Everything went off without a hitch, the computer is fast, and everything (including front light) works great.
(Two quick things: 1. There’s a black sticker that looks like a rounded rectangle that holds the SATA connector to the hard drive itself. Remove that and replace it on the new drive. 2. The antenna cable is difficult to get back on. I’ve done many of these on other Macs. Put the screw back in first and line it up. Be gentle. Persist. You’ll get it.)
You'll get 'em in. Work gently. Make sure they're exactly over top the bottom pins. Press down with a flat smudger. It took me a lot of gentle work to get them in.