That should do, Glenn:
0. Ensure your battery is fully charged
1. Format your SD card in the camera. Switch off your camera
2. Remove your card from the camera.
3. Plug your SD card into a card reader
4. Connect your card reader with your running computer
5. Wait until your Operating System is ready to access the card
6. Copy the firmware file (unzipped!) to the card directly top level, NOT into any of the folders. The filename extension must end in "upd", so the file called something like "m8-2_004.upd". Once written, you should see the file in your file browser
7. Unmount your card from the computer (eject, drag to trash for mac, ...). Don't remove the card before unmounting it
8. Put your card into the camera, close the lid

9. Switch on the camera
10. WAIT THREE SECONDS
11. Confirm the question shown on the camera's LCD
12. WAIT and DON'T TOUCH the M8 until the update is completed
13. Switch off the camera
14. Switch on the camera
15. Format your SD card in the camera
Cheers
Ivo