Chosen Solution
After booting up my Mac, I get a circle with a line through it and every 10 seconds the circle gets replaced with the apple logo and quickly changed back to the circle again. Let the machine sit for a few minutes and still won’t boot
The Prohibitory symbol implies your drive is missing the needed OS your system uses or not setup as the boot drive. About the screens your Mac displays as it starts up The easiest way to fix this is to setup a bootable OS installer I would recommend sticking with Sierra as Apple still has issues with the newer APFS file system used in High Sierra and Mojave on SATA based systems like yours. How to create a bootable macOS Sierra installer drive If you really need a newer macOS I would go directly to Mojave How to create a bootable macOS Mojave installer drive Using it you can refresh your OS or install it.
Has anything changed prior to this issue? I’m experiencing the same thing after doing a SSD swap to replace my DVD drive. If I disconnect the new SSD, the computer boots fine.
