Hi, So, those of you who have updated your 4,1 Mac Pros past El Capitan (and/or have done hex/12-core upgrades) know that there is a firmware tool meant to flash a 4,1 to 5,1 firmware, to make upgrades/updates possible. Here's the problem... I am having a pretty unusual issue with this. I was able to perform this just fine on my first 4,1 Mac Pro (shown in my signature), but my second 4,1 (of the same stock specifications) will not complete the update. Upon starting up, the machine's power light flashes and I let go as soon as I hear the tone; but, without fail, it brings up the normal boot screen once it restarts a second time, rather than bringing up the firmware progress bar. Upon going into System Profiler, I notice that it still identifies as a 4,1 Mac Pro. If I go back to the firmware update tool, it starts me where I was. I've tried this five times in a row, with no luck. How could this be? There's no error or anything - it just simply doesn't work. Has anyone had a similar issue? Any help is appreciated - thanks. -=-=-=-=-=-=-=-=-=-=-=- Specs of my second 4,1: -2x 2.26 GHz quad-core Xeons -8GB 1067 MHz RAM -Mac Radeon 4870 (or whatever the stock one from Apple was at the time) -HDD containing a fresh installation of 10.11 El Capitan (base) --- Post Merged, Jul 29, 2017 --- FYI: I am NOT receiving that common error present with Yosemite+ machines, where the user cannot proceed until he has mounted the Apple Firmware Update package onto his desktop. The firmware updater tool works its magic just fine - I just get no results and without any errors.