Coreboot installed without an issue.
What I did was boot to PureOS Live, on the device I need to resolve this issue with.
I opened a terminal, and followed the the instructions.
Then, I booted to PureOS Live again, and installed PureOS.
I specified to erase the entire disk, and encrypted the disk.
Other than that, I accepted defaults.
Everything went as expected, except now when I boot, I get this:
I doubt there is a hardware issue, since it was running fine on the old PureOS install.
What now?