Catalina installation damaged EFI firmware on MBP mid 2012

why on earth do you link question mark posts as a relevant to EFI problem? question mark means that EFI works totally fine since it is the indication of the absent boot medium. To indicate that, computer needs to actually run EFI bios, check devices, initialise GPU, etc. Failed EFI will NEVER show you a question mark.

Im no Apple fan, but you simply mixing absolutely irrelevant issues together.

also FYI, apple used MXIC Spi ROM chips which can randomly fail, well thats bad but it happens all the time with both PC and Mac devices, also with Winbond. In many cases it will show up during the firmware update since SPI is not able to write a new data even if it worked with an old firmware before. It erases firmware, fails to write new one and here we go - bricked device.

I just spent hours on the phone with Apple support. The issue seems to be how the hard drive is formatted. Every operating system before Catalina had most hard drives formatted as Extended Journaled. Well come to find our that Catalina will not run on that type of formatting. It will only operate on APFS formatting. The only option I was able to do was to reformat my drive to APFS. The good part was that I have a continuous backup of my system since everything is stored in iCloud. I even tried to go back to other operating systems but none of them would recognize my hard drive. So at this point I am currently restoring my drive in APFS and installing Catalina. Hope this helps.

Jim

I wrote about possible ways to fix MacBook bricked by Catalina, including forcing Apple to do it for free (I succeeded but I pressed really strong), having it done at unofficial shop or doing it yourself. See here: https://www.ifixit.com/Answers/View/612997/Catalina+Bricked+my+Mac.+Now+What

After update my MacBook Air 13’ 2012 mid I see black screen and random turn on. The “magic btn combos” didn’t work. Apple please say thuth about the bagged 10.13.4 update and help your clients with notebooks damage in your blame.

I had same issue on MACBOOK PRO (RETINA, 13-INCH, MID 2014).  

I tried a repair in Apple Store in November '19, but only solution is paying for a new motherboard! 

I agree with Smallllk when he say "flashing EFI too complicated" doing it in Store, but why not create a quality program sending affect Mac to a specific assistance to solve it??  

I understand that is very expensive think to a quality program to substitute every motherboard on all affected previous 2015 Mac  occupying hours and hours of work at Genius Bar, but this motherboard are not corrupted!!! 

In the meantime I hope that a solution flashing EFI firmware is considered by Apple, but however I want solve this issue:

Have someone fixed DIY EFI firmware? Can suggest some procedure, some link?

Thanks in advance 

Same here, the Catalina update killed my iMac 2013 too. Is now at Apple for a diagnosis / repair

I have the same problems with my late 2013 iMac.

And, John, do you really think its o.k. to pay 100$ when have you done nothing wrong?

Well, let me tell you that I have the exact same problem ad well a many other people that I Know and on the internet as well. CATALINA upgrade is bricking a lot of devices by ruining the EFI.

My mac mini late 2012 seems to have same problems.

Local authorised reseller says defective LogicBoard replacement for € 450.

Thanks for you info and the hard work. It surely will help many others. My upgrade woriked Ok but I have bluetooth issues.

Is it possible to roll back to old version??

Would you mind telling me what service company you used? Do they have locations across the US or is it purely a local thing? I am having the same issues as you are.

Ah, thanks!

try to install the OS X on hard drive and after that clone to ssd