iMac 27" 2019 - Restart in loop

overshoot

Member
Hi,

I have a customer that came in with an iMac that is restarting in a loop.
The iMac was previously repaired by another shop and I can see the Bios has been reworked somehow.
The customer has reported that the loop happened after he tried to install an SSD in place of the HDD.
Since then the iMac would always restart. The previous apparently did not make it worth since it's doing the same thing.

I am getting the following messages in verbose before it restarts:

- Failed to wake the ME
- Begin GFX firmware load process

And these messages will repeat themselves.

Seeing "ME" in the logs + having the bios reworked, I am assuming the Bios was messed up and replaced with one from another board without the ME region being cleaned up.
I would like to rule that out first before assuming there could be a fault with the GPU (as can be seen with the following message)

Can you please clean the ME region for me on this bios: https://drive.google.com/file/d/123yLS9KLLxrOOqSwCRLEmKg-PDEW_D3k/view?usp=sharing
Thank you in advance.
 

overshoot

Member
Ok I will get my customer to call them and ask, then report back.

What if I can't get that information or at least know the truth?!
I understand you don't want to reuse the Bios from a machine that is currently being used and I'll make sure the SN matches the one under the case if that makes any difference.
 

2informaticos

Administrator
Staff member
I'm not in my office for several days.
So I don't have full access to al my stuff.
I can try to build something in the night.
 

overshoot

Member
Well enjoy your holidays then! ;-)

The shop said they have put back the original Bios dump.
If you are busy and can't do it, maybe you can point me a link which explains how to do it?
 

overshoot

Member
Hi,

If you are back and can help with it, please do.
I am getting lost with these new ME/PMC stuff and Piernov's video is obsolete with the newer chipsets.

I've followed the guide on WinRaid for CSME v12 and had an cse_image_fwu_base.bin but I don't know what to do with it.
I understand you need to use fwupdate tool but that's about it.
 

overshoot

Member
Hi 2informaticos,
No worries at all.
I am actually very sorry to hear that you are in the hospital.
I hope you are fine.
Thank you for doing it.
 

overshoot

Member
Ok it worked. Thank you a bunch!

Actually if I understand what you did, you simply added the ME region which is smaller in size (1.2MB) than the one originally in the Bios dump (1.7MB) in the decomp folder of the FIT software right?
There was no need to do that cse_image_fwu_base.bin file.
I got tricked by the file size and was looking to create an identical in size ME region and the one on the Win-Raid webpage was 1.2MB so I thought I was missing something...
 
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