... looks like the process has been successful. Pin 1 was indeed the bottom left one in the picture. I couldn't locate the MSDM in the existing BIOS extracted, and the chip was not fully identified / supported by the flashrom tool, but everything went well. Now I'm left with the final issue of the screen inversion in Windows 10, but that's a driver issue not a power / BIOS / bricking.
Thanks Bodger... wherever you went!