I would like to ask for some help from the community. While working to resolve other issues, I have found that the Mac will not startup in diagnostics mode.
I am pressing and holding the D key during startup, as described in 102603.
The Mac
What I would ask is next steps to get the iMac running Apple Diagnostics. I am looking at starting up from a backup volume to reload Mac OS. Thank you, iGardener.
iMac 27″, macOS 15.4
Try rebooting with Option-D to start the utility over internet.
If you are using a wireless keyboard, try using a USB keyboard. Wireless keyboards may not respond quickly enough to trigger startup commands. If you are using an Apple Magic Keyboard, connect the keyboard to the Mac with its charging cable and it should function as a USB keyboard.
Try rebooting with Option-D to start the utility over internet.
If you are using a wireless keyboard, try using a USB keyboard. Wireless keyboards may not respond quickly enough to trigger startup commands. If you are using an Apple Magic Keyboard, connect the keyboard to the Mac with its charging cable and it should function as a USB keyboard.
Thank you D.I. Johnson. Apple Magic Keyboard plus the USB cable worked fine. No problems detected by diagnostics. Continuing to getsupport.apple.com did launch the limited version of Safari available in recovery mode. However the site never populated. On next startup the machine crashed. The crash report made reference to a kernel panic. On next startup after that the machine is OK.
Thank you. Bad drive cable. I can check for that. I've just disconnected the Time Machine backup drive. Next step I'll disconnect the other devices.
Kernel panics are usually a sign of a hardware problem or conflict.
If you have external devices and peripherals connected to the Mac, you can troubleshoot by shutting down the Mac and disconnecting everything. Then connect items one at a time, rebooting and working on the Mac for a bit. If no panic occurs, you can connect the next device and restarting.
Very often it is discovered that a bad drive cable or adapter is the problem.
Mac will not startup in diagnostic mode
