820-00164 Won't Install Firmware Update

[hambook]

I have an A1465 on my bench with a really weird issue. It came in because the customer tried to update to Big Sur and the update failed and split his OS partition into 3. I backed up the data and wiped/tried to install Monterey from a freshly downloaded App Store copy on a USB drive and it fails after 5 mins saying "there was an error while loading the update". I tried installing Big Sur, and it gets further, but when it gets to the part where it boots into "recovery" to install a firmware update, the update immediately fails and the system restarts to the installer screen. I've tried connecting to WiFi and plugging in a Thunderbolt to ethernet cable, both to no avail. Have tried multiple downloads of the OS, multiple SSDs (internal and external). Current SSD is an original Apple 250GB. Board looks clean, no signs of liquid or corrosion. Does this sound like a wonky BIOS chip? What else could cause something like this?

 

[2informaticos]

Many times BIOS gets corrupted when installing newer macOS version.
You should start reflashing the BIOS.

Did you try to install older macOS, not Big Sur?

 

[hambook]

Will give that a shot!

Sorry, forgot to mention - tried as far back as High Sierra. Got high Sierra to update to Mojave, but not any further.

 

[hambook]

Hmm, tried a file from here on the forum and one from BadCaps, both of them lead to the board cycling power. Couldn't find any other ones (they lead to dead links), do you know if there are any other files out there I can try? I have a backup of the original BIOS as well, but if the chip was potentially corrupted would this even be any good for anything?

 

[2informaticos]

That file is reported as working.
So you must have other problem than BIOS.

"Got high Sierra to update to Mojave, but not any further."
So you can install High Sierra from USB and upgrade to Mojave correctly?
Only fails to upgrade Big Sur?

 

[hambook]

That is correct - HS installed fine and upgraded to Mojave, but the Big Sur update fails.

Re-flashed the original BIOS just to make sure I didn't damage anything on the board, and we're back to square one with the board booting but not updating. Also definitely see the value in a Medusa now, would be very nice to not have to remove the chip from the board.

 

[2informaticos]

Probably not worth to install Big Sur on that machine.
Do you REALLY need that?

 

[hambook]

That's a very good point. I will have a chat with the customer and explain he probably won't get much of a benefit. Thanks for your thoughts on this one, appreciate it.