Many times we have all asked ourselves “why don't I investigate how to create a jailbreak? Maybe I can create it myself ”.
The answer for most of us is NO, creating a jailbreak, and especially a jailbreak at the bootrom level is very difficult, and for example i0n1c has made this presentation where it says that it is necessary to search for an exploit of this type, both at the level of necessary hardware and software.
Most of you will not understand almost anything, some with sufficient computer knowledge will appreciate the difficulty of the process.
Here you can see the complete presentation.