Press the Power button and immediately begin tapping the F12 (or F2 ) key repeatedly—about twice per second.
If you need to change the permanent boot order rather than just a one-time override, use the key during startup to enter the BIOS/UEFI Setup Utility . Common Troubleshooting Tips
The key is the standard "boot button" for Toshiba and Dynabook laptops, used to access the Boot Menu . This feature allows you to bypass the primary hard drive and boot from a USB drive, CD/DVD, or network. How to Use the Toshiba Boot Button To use the F12 boot feature, follow these steps: