Thanks!
Just started the HighSierra installer, and it went straight to Firmware update. So i tried that. Hope it works.
I will try the EFI rebuild again after that.
Is there any way to reconstruct the EFI if there is still some corruption there?
Yes.
After the update it reads MP51.0089.B00
I was under assumption it would read something else?
High Sierra most recent BootROM is MP51.0089.B00, while Mojave is 144.0.0.0.0. You need to update it to 144.0.0.0.0 before injecting EnableGop.