I need to flash my BIOS again or enable legacy ROM

Hello! I have a Acer R11 (C738T) and I have flashed the BIOS once with Mr.Chromebox (Version 4.22). I need to flash it again or enable Legacy ROM’s So I can install Windows 7.

there is no legacy BIOS support, nor Windows 7 support, for that or any ChromeOS device.

If you need Win7, run it in a VM.

Thanks!