If you have a problem such as a Boot Issue or a recurring Blue Screen.
It is always best to run diagnostics from a systems UEFI BIOS as it allows one to differentiate between problems caused by hardware failure and software issues. To access Lenovo UEFI Preboot diagnostics power down your Lenovo and tap [F10] repeatedly when powering it up:
The Preboot Diagnostics User Interface will now show:
It is always advised to Run All the tests:
Press the [↓] key until Run All is highlighted and press [Enter]:
It is recommended to run the extended tests:
Press the [↓] key until Extended Tests is highlighted and press [Enter]:
It will now take time to run the tests:
In my case all the tests pass meaning the blue screens this Yoga 14 (20DM) on a factory image of Windows 8 Upgraded to Windows 10 were more likely due to software and not the underlying hardware. If you have a hardware issue it should display an error message instead which you can contact Lenovo to rectify. I can press [Esc] to exit:
Then press the [→] and [↓] keys to highlight “Exit application” and press [Enter]:
In my case, as I have no hardware issue but a software issue, I am going to clean install Windows 10 Version 1809 on this system directly (opposed to a series of in place upgrade installs).