Fast Repair for Storage Upgrade Success
MacBook Pro worked fine with stock hard disk but refused to boot with SSD in place. Even erasing SSD was finicky and produced partitioning errors I'd never before seen.
Easy! In troubleshooting, I happened to have another client's same-model Mac on hand to briefly swap in their storage data cable and verify that it worked. So, I'd done the repair once already when it came time to do it with the replacement from iFixit. I was impressed at how quickly I was able to complete the job, and my client was super grateful, too.
This was my first time experiencing a bad storage data cable. My best guess about the SSD problems experienced initially was that because the new drive worked faster than the old, the bad cable was unable to handle the increased throughput. If you come upon weird partitioning errors when managing a drive or find that an old drive works fine but a new drive doesn't, consider that the drives may not be at fault and check the data cable instead.