error occurred while verifying firmware?

i have ran into an issue where a 2015 13" apple macbook pro will not upgrade to mac os mojave.

i've tried everything i can think of from replacing the ssd, creating a bootable external drive downloading the upgrade package and running from there, internet recovery install of OSX yosemite then download the upgrade and run, trying to run the upgrade in safe boot. no matter what i do i get the same problem.

the laptop restarts a couple times then loads to an error window (see pic).

i contacted apple they escalated my case to a specialist who was really awesome. We did a couple installs in various ways and ended up in the same spot every time. We ended up creating and sending some log files in to him and i was told it needed to go to the engineering department and they would get back to me with in 48hrs.

48hrs passed so i reached out just to check if there was any update on the case. i found that the original specialist would not be available until september 2+ months out via his voice mail and to call back in.

i called back in and was sent to a different specialist named Yaya. who pretty much treated me like an idiot. i was told that i needed to reinstall and upgrade back to Mac OS sierra and wait for an update that would fix this issue. i asked it there was an eta on that and was told that "i dont have a magic ball and cant predict the future" thanks yaya!

has anyone had this issue and found a solution? im guessing the Geniuses wont be able to help at this point.