Can't complete Lubuntu 14.04 install on Mac Powerbook G4 12" laptop, powers off

Hi all,

I am trying to install Lubuntu Desktop 14.04 desktop on an old Mac Powerbook G4 12" laptop, but have gone as far as I (seemingly) can and now stumped.

Booting successfully from a USB drive (via Open Firmware), and managed to solve the graphics and wireless issues to display the desktop with correct colours and connect to the internet. Wheee!

Ran the installation procedure, choosing one of the default partition options (don't want to keep a Mac partition at this stage because I no longer have the install disks). Got to the point of "copying files" but when the progress bar hit the end the machine just powered off. This happened twice in a row.

Thought it might be the default partition scheme, so I tried to set up partitions as discussed in the FAQ at https://wiki.ubuntu.com/PowerPCFAQ but I can't seem to get the right combination to allow the installation to proceed. Don't really know enough about the file system architecture to make this work

Can't find any similar issues reported in the FAQ, Known Issues, forums, or elsewhere. Anyone else run into the same problem? Any tips or alternative approaches I might consider?

Thanks
Duncan