I though I would post this information here for historical purposes in case it might help someone.
In October 2020 I noticed my Mac mini was behaving oddly. My display would occasionally black out for a few seconds, audio would sometime glitch out and get all crackly. I also started seeing external hard drive disconnects and sometimes an external drive would not be connected after a restart and I would have to unplug and plug it back in.
I figured these were perhaps related to my recent update to Catalina and they did not happen often so I didn't worry about them.
At the end of December I was preparing to upgrade to Big Sur and found that rebooting was talking a long time, perhaps 30+ seconds to get to the login screen and then another 2-3 minutes before the keyboard and mouse would become responsive so that I could login.
After running a hardware diagnostic (reboot Mac mini and hold down the D key), I got this message:
I switched my display to HDMI (from USB-C) and got the message a 2nd time.
I made a Genius Bar appointment at my local Apple Store (earliest available was 6 days away!) which gave me plenty of time to clone the internal drive to an external SSD and remove my 64GB RAM and put back in the original 8GB RAM.
When I brought the Mac mini in, they did not even test it themselves. I showed them a picture of the hardware diagnostic error screen and they immediately ordered a replacement logic board. I have AppleCare on this so there was no cost to me.
Fortunately, this arrived quickly. 2 days later I got a call saying the Mac mini was ready for pickup.
Invoice shows cost of repair would have been $369 for the logic board and $79 for labor had I not had AppleCare.
I restored the Mac mini from the clone, upgraded to Big Sur and put the RAM back in. Things are working great now. Boot time is down to about 10 seconds.
I hope these details might be helpful to someone. Moral of the story is to run that hardware diagnostic first! Before I did that I wasted time on trying clean installs of Catalina and Big Sur on external drives to rule out software issues.
In October 2020 I noticed my Mac mini was behaving oddly. My display would occasionally black out for a few seconds, audio would sometime glitch out and get all crackly. I also started seeing external hard drive disconnects and sometimes an external drive would not be connected after a restart and I would have to unplug and plug it back in.
I figured these were perhaps related to my recent update to Catalina and they did not happen often so I didn't worry about them.
At the end of December I was preparing to upgrade to Big Sur and found that rebooting was talking a long time, perhaps 30+ seconds to get to the login screen and then another 2-3 minutes before the keyboard and mouse would become responsive so that I could login.
After running a hardware diagnostic (reboot Mac mini and hold down the D key), I got this message:
I switched my display to HDMI (from USB-C) and got the message a 2nd time.
I made a Genius Bar appointment at my local Apple Store (earliest available was 6 days away!) which gave me plenty of time to clone the internal drive to an external SSD and remove my 64GB RAM and put back in the original 8GB RAM.
When I brought the Mac mini in, they did not even test it themselves. I showed them a picture of the hardware diagnostic error screen and they immediately ordered a replacement logic board. I have AppleCare on this so there was no cost to me.
Fortunately, this arrived quickly. 2 days later I got a call saying the Mac mini was ready for pickup.
Invoice shows cost of repair would have been $369 for the logic board and $79 for labor had I not had AppleCare.
I restored the Mac mini from the clone, upgraded to Big Sur and put the RAM back in. Things are working great now. Boot time is down to about 10 seconds.
I hope these details might be helpful to someone. Moral of the story is to run that hardware diagnostic first! Before I did that I wasted time on trying clean installs of Catalina and Big Sur on external drives to rule out software issues.
