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I initially did an erase and install with disk utility and the computer booted up fine. The next day I got the blinking question mark in the folder at start up. I restarted and since then I’ve got nothing but the black screen. I have tried to boot in recovery (command R) I have gone through the NVRAM and PRAM reset protocols. Nothing. I have created a bootable thumb drive with Mojave on it and tried to boot to the thumb drive. Nothing. I don’t know what OS is on the device. It may have been High Sierra. I have a new drive, not installed yet, and can make a bootable drive with High Sierra on it. Can any one assist with some step by step instructions as to what can be tried next?
I think you need to go back one more version as High Sierra is the first release of APFS. You should create a bootable OS installer with Sierra as that’s the last HFS+ release. The systems firmware likely didn’t get updated so it has no idea how to boot up under anything else but HFS+ OK, here’s a link to the older OS versions How to get old versions of macOS Download the Sierra installer Now format a 32GB Thumb drive with GUID and a journaled file system using your working Mac. Then follow this guide to create the bootable Image How to create a bootable macOS Sierra installer drive Now give that a try!
