Macbook2,1 has 32bit EFI.
Normal grub tries to install 64bit efi loader, so
You need to Install grub-efi-ia32 and run grub-install.
Here I have a bookmark which describes the whole installation process on Macbook2,1.
I have a 2007 MacBook3,1 myself. I’m afraid you’re probably expecting too much from a machine that Apple decided was obsolete way back in 2012 when macOS 10.8 Mountain Lion came out. It was stuck on 10.7 Lion and getting pretty useless as far as current web browser support. It’s kind of a miracle that it still works as well as it does. It only has the basic ...
OK thank you to all who read this, I have now found the problem. It seems that starting Epiphany causes the system to hang. I had though that as that was the browser that came with the installation it should be OK but on my 2009 MacBook Pro it causes instability. I'm now using Firefox and that's working fine.