Buying a Used Mac – Only InfotechBoot

What's up r/mac,

I'm pretty solid with technology, and saw a deal on Craigslist a few days ago I couldn't pass over without further investigation.

Effectively, a 5k iMac from late 2015 that had been sitting in an elderly person's home, who was cleaning out their house incase something happened to them (so their family wouldn't have to do it after they died). Pretty forward thinking, to be honest.

Anyway, iMac was in pristine condition and had been used for email and web browsing. I poked around, ran disk utility, everything checked out so I paid the $500 and brought it home.

Immediately wiped and installed High Sierra from a USB drive. Saw that APFS was an option to use for the filesystem, and even though I remember the whole fusion drive APFS debacle from a year or two ago, I went for it.

Long story short, the iMac was throwing errors after that. Took me a solid two days of reformatting and reinstalling in various ways and versions to finally get the errors to stop.

Not being completely satisfied that there actually wasn't a problem with the hardware, I called Apple Support and setup a Genius Bar appointment.

I live in Maine, and our local Apple Store is over 2.5 hours away. Thinking to myself that they're probably just going to run some diagnostics on the computer before opening it up and replacing any parts (which would result in another trip home and back to the store), I called Apple support one more time.

The woman was very friendly, and ended up having me boot the iMac holding down the "D" key. I had never had to dig this far to determine if there was a problem or not, and it basically boots the computer into a mode that will check all the hardware individually, and throw up any codes at the end of it.

Just wanted to share about the "D" key on boot incase anyone else needs to determine the status of their hardware before opening up a Mac. Been a few days since then and no more errors, no issues at all.

How to use Apple Diagnostics on your Mac

Apple Diagnostics: Reference Codes