Restart your system and hold the '''D''' key to launch the built-in diagnostics. If that fails then you’ll need to launch your system with a newer version of MacOS as Apple did have a bug in some OS versions for the diagnostics to work properly.
+
Restart your system and hold the '''D''' key to launch the built-in diagnostics.
If that fails then you’ll need to launch your system with a newer version of MacOS as Apple did have a bug in some OS versions for the diagnostics to work properly.
+
+
Here’s a bit more on this mess [https://github.com/upekkha/AppleHardwareTest|Fixing Apple Hardware Test (AHT)]
Restart your system and hold the '''D''' key to launch the built-in diagnostics.
+
Restart your system and hold the '''D''' key to launch the built-in diagnostics. If that fails then you’ll need to launch your system with a newer version of MacOS as Apple did have a bug in some OS versions for the diagnostics to work properly.
Restart your system and hold the '''D''' key to launch the built-in diagnostics.
Reference: [https://support.apple.com/en-us/HT201255|Mac startup key combinations]