How to update the EFI firmware of a replacement logic board of a MBP mid-2015 to make it compatible with Mojave? Apple has put me in a pickle. I had a lot of parts (battery, display, logic board) of my MBP mid-2015 replaced at the local Apple Store. When it was returned to me, it had a big new problem: it would keep booting into internet recovery mode (although it eventually did boot), but eventually ended up freezing while I was using it. Trying to reboot into recovery mode put me in the same internet recovery cycle

However, it turns out that my MBP runs fine from a bootable external backup SSD over USB. Since running Disk First Aid at that point found no errors on the internal SSD, I thought I would try to reinstall Mojave from the SSD, but when I did so, the installer refused, informing me that my Mac had an incompatible firmware version and suggesting that I try to install Mojave on a HFS+ disk! (alas, my MBP's flash drive is formatted as APFS encrypted). It was then that I realized that what must have happened is that the replacement motherboard has an earlier firmware version that is incompatible with OS X 10.14.1 installed on the MBP's internal flash drive, and the so-called "geniuses" at the Apple Store didn't think about this.

The problem is this: how can I update the logic board firmware so that it is compatible with Mojave? I just tried an internet recovery install of Mojave, but the installer refused for the same reasons as before (incompatible firmware). I can't even see a way to downgrade the internal flash drive to HFS+ …

Is my MBP able to run from the external SSD because it happens over USB, or because that SSD happens not to be encrypted?
Let me outline the solution here in case any one else encounters the same problem.

The installer wouldn’t allow me to select the internal flash drive of my MacBook Pro, and the precise installer error message was “This Mac needs a firmware update in order to install to this volume. Please select a Mac OS Extended (Journaled) volume instead.”

So there were 2 solutions:


Backup the internal flash drive, erase, reformat as HFS+, and run the installer again.
Install Mojave on an external HFS+-formatted drive.


Explanation: with the “stock” firmware of a replacement logic board, the installer expects an HFS+-formatted drive, and won’t update the firmware until it can install the OS on an HFS+-formatted drive.