Here is my very sad story.
I have a Macbook pro 13" retina early 2015 (MB 12,1).
My bootrom version is MBP121.0167.B07 and according to this ( https://docs.google.com/spreadsheets/d/1qGRVF1aRokQgm_LuTsFUN2Knrh0Sd3Gp0ziC_VIWqoM/htmlview ) table I'm running a veeery old firmware, updated to yosemite.
I found this problem while I tried to upgrade to mojave (I'm runnig Sierra right now). Error while verifying the firmware.
After many tries and repairs to the disk, I found the problem: my firmware.
So i tried many thing to update it. Install mojave on a external drive didn't help (same firmware error). I tried to boot with mojave using carbon clone (I cloned the hard drive from my girlfriend's macbook updated to mojave). I also tried to do a update while in mojave, but nothing.
I tried a fresh install of sierra, but no firmware updates. I tried to use El Capitan from a external drive, still nothing.
I tried some tool to install the firmware right from highsierra installer, nothing.
I tried to install it manually with bless command. The output was good, it sets the nvram to install the update after the reboot but nothing.
What should I do? Change the logic-board seems expensive and stupid if the problem is just a upgrade.
Thanks everyone.
Best Answer
Your question does miss some key details, so this answer makes the following assumptions:
Essentially, some years back Apple started automatically including firmware updates (if/when required) within macOS updates/upgrades. And, with the move to the APFS file system, firmware updates were required on pre-existing Macs with SSD drives to support macOS High Sierra (and above) as they required APFS to be installed. So, cutting a long story short, you're most likely missing this firmware update.
Since you've already gone through quite a bit of frustration, your best bet is to go through a total reinstall process. My recommendation would be to do as follows:
* This specific key combination will install the latest version of macOS compatible with your model Mac, which presently is macOS Mojave.