Hello,
Could someone look at this and see if it appears to be corrupted?
I’m troubleshooting an iMac that was working fine and then there was a series of power outages and afterwards the iMac does not POST. Diagnostic LED #1 and #2 are illuminated, but not #3. I did a quick visual inspection of the logic board and found no visibly bad/burned components and found no shorts. I swapped RAM and CPU with a known good and still behaves the same. I have also reset NVRAM and SMC numerous times.
The lack of Diagnostic LED#3 is supposed to mean “logic board unable to communicate with GPU”, but if the computer wasn’t POSTing due to a corrupt BIOS, it would behave like this as well. I thought it could be a corrupt EFI.
Looking at my dump in UEFITool, the parser indicates that there may be some corruption, but I honestly don’t know enough about BIOS/EFI/UEFI editing/repairing or UEFITool to interpret the parser output, but the wording certainly makes it sound like something isn’t right.
I’m attaching a dump of my original EFI which I suspect is corrupt as well as a supposedly clean EFI I found online for this model and finally, a screenshot of the parser output in UEFITool. It's interesting that when opening the "clean" EFI in UEFITool, the parser does not have the same errors as my original one does. I don't know if that means anything or not.
I was hoping someone experienced with Apple EFI corruption could just look at what I have here and help guide me in the right direction. Right now, it appears that the EFI seems to be corrupt, so I need to get this fixed and then observe the iMac behavior after I flash a new EFI to the chip and then potentially resume troubleshooting once I know the EFI is good if it doesn't fix my problem.
Thank you.
Could someone look at this and see if it appears to be corrupted?
I’m troubleshooting an iMac that was working fine and then there was a series of power outages and afterwards the iMac does not POST. Diagnostic LED #1 and #2 are illuminated, but not #3. I did a quick visual inspection of the logic board and found no visibly bad/burned components and found no shorts. I swapped RAM and CPU with a known good and still behaves the same. I have also reset NVRAM and SMC numerous times.
The lack of Diagnostic LED#3 is supposed to mean “logic board unable to communicate with GPU”, but if the computer wasn’t POSTing due to a corrupt BIOS, it would behave like this as well. I thought it could be a corrupt EFI.
Looking at my dump in UEFITool, the parser indicates that there may be some corruption, but I honestly don’t know enough about BIOS/EFI/UEFI editing/repairing or UEFITool to interpret the parser output, but the wording certainly makes it sound like something isn’t right.
I’m attaching a dump of my original EFI which I suspect is corrupt as well as a supposedly clean EFI I found online for this model and finally, a screenshot of the parser output in UEFITool. It's interesting that when opening the "clean" EFI in UEFITool, the parser does not have the same errors as my original one does. I don't know if that means anything or not.
I was hoping someone experienced with Apple EFI corruption could just look at what I have here and help guide me in the right direction. Right now, it appears that the EFI seems to be corrupt, so I need to get this fixed and then observe the iMac behavior after I flash a new EFI to the chip and then potentially resume troubleshooting once I know the EFI is good if it doesn't fix my problem.
Thank you.
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