Chosen Solution
I have a problem. This MacBook needs a newer firmware and it just wont boot from internal ssd (replaced) and the firmware is from 2015. The new firmware included with El Cap and newer doesn’t install. It fails to verify the firmware or fails to update it. Is there anything I can do for this poor MacBook
You’ll need to setup a bootable OS installer USB thumb drive. Download from another Mac the installer from here How to get old versions of macOS I would recommend going with Mojave, follow this guide to create the How to create a bootable macOS Mojave installer drive
