My sister's Mac was broken

My Problem

Mac didn't boot, couldn't find the drive, a new-ish SSD I had installed previously. Sure enough, when plugged into another computer, the drive showed up, leading me to believe the culprit was the cable.

My Fix

Easy, remove back plate, remove old cable, slap in new cable, screw on back plate. Realize the you didn't put the drive back in, remove the back again, add drive, screw on back again.

My Advice

The unibody macbook pro shares a product code (A1278 ) with the unibody macbook from a similar era, don't accidentally order that hard drive cable like I did.