The master CPU of the Rasberry Pi 1-4 is the VideoCore GPU, not the Arm. The "firmware" is the now-Microsoft-owned, proprietary, ThreadX RTOS: https://en.wiki

The master CPU of the Rasberry Pi 1-4 is the VideoCore GPU, not the Arm. The "firmware" is the now-Microsoft-owned, proprietary, ThreadX RTOS: https://en.wikipedia.org/wiki/ThreadX https://en.wikipedia.org/wiki/ThreadX The Arm doesn't start the computer and you can't run any firmware on the Arm that will change this.