You can change the boot order in the current version of BIOS, flashing BIOS is risky and must be done with care. It may render your pc inoperable.
You must get the right version of BIOS from the manufacturer, unzip it to your desktop, disable all background services, disconnect Internet,close all opened windows, disable AV, right click the flash.exe file(or similar) which is in your desktop click "run as admin". You shouldn't touch the mouse or keyboard while flashing(just walk away from your pc) and cross your fingers. Good luck.