I´m getting old (30 years old) 
and I´m trying to understand how the Android boot works.
For me, the concept about inicialize a system, in a few words, is:
1. The BIOS inicialize the mains components (like a RAM, Video, etc);
2. After that, call a bootsector of HD;
3. On bootsector are present a bootmanager (MBR, Grub, etc), who is responsable to "identify" and start the OS (like a Windows ou Linux).
4. The OS start and the magic happens.
Some things are very simple to assume:
1. You don't need modify (unlock) or replace the BIOs, because it just inicialize the computer.
2. After BIOS you have a bootmanager and you can modify or replace it as many times as you want.
3. Change the OS doesn't brick my PC.
I readed a lot of articles about inicialization and partitions, but I can't understand why the smartphones bricks?
Now, the questions:
1. So, WHY the smartphones bricks?
2. Do Hard brick happens in bootloader process or before?
3. Why do I need unlock the bootloader?
4. Does the custom ROMs change the bootloader? If, yes and assume the bootloader hard brick the devices, why the Custom ROMs doesn't create a bootmanager after the bootloader official (as Grub call MBR)?
5. Can I replace the smartphone "BIOS"?
I spend a lot of money in a Atrix 2, and I really want understand how this things works to customize it.
and I´m trying to understand how the Android boot works.For me, the concept about inicialize a system, in a few words, is:
1. The BIOS inicialize the mains components (like a RAM, Video, etc);
2. After that, call a bootsector of HD;
3. On bootsector are present a bootmanager (MBR, Grub, etc), who is responsable to "identify" and start the OS (like a Windows ou Linux).
4. The OS start and the magic happens.
Some things are very simple to assume:
1. You don't need modify (unlock) or replace the BIOs, because it just inicialize the computer.
2. After BIOS you have a bootmanager and you can modify or replace it as many times as you want.
3. Change the OS doesn't brick my PC.
I readed a lot of articles about inicialization and partitions, but I can't understand why the smartphones bricks?
Now, the questions:
1. So, WHY the smartphones bricks?
2. Do Hard brick happens in bootloader process or before?
3. Why do I need unlock the bootloader?
4. Does the custom ROMs change the bootloader? If, yes and assume the bootloader hard brick the devices, why the Custom ROMs doesn't create a bootmanager after the bootloader official (as Grub call MBR)?
5. Can I replace the smartphone "BIOS"?
I spend a lot of money in a Atrix 2, and I really want understand how this things works to customize it.
