Not a Parkour related blog post today but hopefully this will be of use to someone else out there struggling with the same issue.

The Problem:
After updating to windows 8.1 or a restoring to a previous version of windows, it is no longer possible to access BIOS using any method, including the ‘one key support’ button on the side of the laptop.

The Cause:UEFI BIOS has been corrupted and must be re-flashed.

The SolutionFlash the bios with the utility linked below. Unzip the file, ensure the laptop is plugged into the mains, run the .exe file. Leave all settings as default and click button to begin. Update will commence and windows will reboot.

Upon completion it will once again be possible to access the bios by turning on the computer using the ‘one key support’ button and accessing it through the boot options menu.
Download link: www.streetmotion.co.uk/downloads/65cn99ww.zip

Disclaimer
This is an official lenovo patch which was issued on their uk support site but later removed. This installed first time with no issues on my Lenovo U410 Touch Ultrabook and fixed the problem allowing me to boot into the bios setup again and make changes.

There is no guarantee that this will work on your particular ultrabook and you understand that by downloading and running this file there is a small chance you may turn your shiny laptop into a very expensive aluminum brick.