From VyOS Wiki
- Write the official ISO to a USB drive of some sort.
- Plug in VGA, power, USB keyboard, and USB drive.
- Press the "SW" button on the front (this is the power button; I don't know what "SW" is supposed to mean).
- Begin rapidly pressing Delete on the keyboard. The boot prompt is very quick, but with a few tries you should be able to get into the BIOS.
- Chipset > South Bridge > USB Configuration: set XHCI to Disabled and USB 2.0 (EHCI) to Enabled. Without doing this, the USB drive won't boot.
- Boot to the VyOS installer and install as usual.
- Warning the interface labels on my device are backwards; the left-most "LAN4" port is eth0 and the right-most "LAN1" port is eth3.