Chosen Solution
After pressing the power button I’m greeted with a greyish blue screen with a circle and a line through it. It then flashes with the apple logo and a folder with a question mark and gets stuck in a flashing loop.
A prohibitory symbol, which looks like a circle with a line or slash through it, means that your startup disk contains a Mac operating system, but it’s not a version or build of macOS that your Mac can use.
