Step 1, If can't booting from Ubuntu bootable disk, please change BIOS Setting to allow booting from Ubuntu bootable disk.(Gemini Lake J4125 & J4105 & N4020 & N4000,no need to set BIOS for other platforms)
A. Press the power button and press F7 or Delete continuously to enter select boot device menu -> select Enter Setup and press Enter to enter into BIOS Setting menu.
B.BIOS Setting ->Chipset ->Common Function ->OS Selection ->Select Intel Linux.
C.BIOS Setting ->Chipset ->South Cluster Configuration ->Miscellaneous Configuration ->8254 Clock Gating ->Select Disable to disable 8254 Clock Gating.
D. Press F4 to save and exit.
Step 2,Create a Ubuntu 20.04 LTS bootable USB flash disk.
Use a third-party tool to create a Ubuntu 20.04 LTS bootable USB flash disk, like UltraISO.
A.Run UltraISO on your PC.
B. Click File->Open to open the Ubuntu 20.04 LTS image.
C. Click Bootable-> Write Disk Image->Write to create a Ubuntu 20.04 LTS bootable USB flash disk.
Step 3,Install Ubuntu 20.04 LTS.
A. Plug the Ubuntu bootable USB flash disk into MiniPC, connect a keyboard.
Then connect the MiniPC to TV with HDMI cable.
B. Press the power button and press F7 or Delete continuously to enter into select boot device menu. Select your USB flash disk to install Ubuntu.
C.Select “Ubuntu” or “OEM install(for manufacturers)” to install Ubuntu.
Select Install Ubuntu.
Choose keyboard layout.
Select updates and software.
If you want to save installation time, do not tick Download updates.
Select installation type.
Select your location.
Set up your name and password. And then click Continue.
After system Installation Complete, click Restart Now.
Remove the installation medium,then press Enter.
If you select “OEM install(for manufacturers)” , you will get a tool “Prepare for shipping to end user” on the desktop. This tool will restore all the settings during system installation. And the end user can set their own account, password,language,location and keyboard layout.
Double click “Prepare for shipping to end user”, input your password and click Authenticate to restore all the settings.
When finished, select shutdown.