Apple Event: May 7th at 7 am PT
Intel iMac displays message "Your computer restarted because of a problem. Press a key or wait a few seconds to continue starting up." After 6 attempts it displays a no entry sign, then repeats. How can I break into this infinite loop?
iMac 21.5″, macOS 10.15
My first guess is that you likely have a bad hard drive especially if the iMac is using a hard drive. At the very least it appears either the file system or macOS is damaged since the no entry sign means a bootable OS is seen, but it is either damaged or not compatible. You can try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the diagnostics don't detect all drive failures. It is possible to check the health of the drive by creating & using a bootable Linux USB stick depending on the exact model of your Mac. I can provide instructions if interested.
Here is an Apple article on how to deal with various startup issues (assuming the drive is healthy of course):
If your Mac doesn't start up all the way - Apple Support
I hope you have a good backup already. If you don't, then as soon as possible make a backup. If you have access to another Mac, then it may be possible to access the data by putting the iMac into Target Disk Mode (as long as the drive is healthy).
My first guess is that you likely have a bad hard drive especially if the iMac is using a hard drive. At the very least it appears either the file system or macOS is damaged since the no entry sign means a bootable OS is seen, but it is either damaged or not compatible. You can try running the Apple Diagnostics to see if any hardware issues are detected. Unfortunately the diagnostics don't detect all drive failures. It is possible to check the health of the drive by creating & using a bootable Linux USB stick depending on the exact model of your Mac. I can provide instructions if interested.
Here is an Apple article on how to deal with various startup issues (assuming the drive is healthy of course):
If your Mac doesn't start up all the way - Apple Support
I hope you have a good backup already. If you don't, then as soon as possible make a backup. If you have access to another Mac, then it may be possible to access the data by putting the iMac into Target Disk Mode (as long as the drive is healthy).
Thanks for the suggestions. I do have a Time Machine backup, used to populate this Silicon iMac. I had already tried to start the Intel iMac in recovery mode unsuccessfully but after reading the Apple article I tried again using a different keyboard that connects to the computer via a USB cable. It worked! However, disk utility was unable to erase the hard drive, giving the reason that the hard drive is in use by process 636 (kext cache). I tried again with the same result except that the kext cache process was now 674. Any further suggestions?
Success! I returned to the Intel iMac and did disk first aid before trying disk erase again. This time disk erase worked. Used space is 24,576 bytes, file count 1.
Intel iMac restarts repeatedly
