Question about the role of BIOS, ME, EC in a computer

Well, I bricked my PC a few days ago when I was trying to mod my BIOS.

I was thought of buying a CH341A, but my parents got distrust of me, take my computer to a computer repair shop, and the technician said I fried both the CPU and motherboard, requiring replacements.
He said BIOS, [ME and] EC, and software, firmware in general, don’t play any role in powering on the CPU, also the role of the BIOS [and ME] is to set the date and time, “booting Windows”, EC also only control the fan speed, nothing else. Furthermore, the reason it is fried is that I’m setting the “Service mode” jumper.

So I’m wondering what’s the function of BIOS, ME and EC in booting a computer?

Most of the repair shops do at most a flash of a firmware image of a similar machine / board or do nothing at all. Some refuse completely to work in this area and sell new parts.
The information you got about ME / bios region / firmware functions is at least incomplete if not wrong, but it might have gone through some filters (your parents, your limited knowledge…)

Read the forum, there’s some guides about ME- function, updating updating and reconfiguring. Otherwise there’s quite a lot of information via search engines.

Haven’t seen many destroyed cpus and boards directly after flashing ‘something’.

But unclear what you did and unclear what happened.

Do you still have the image you flashed and the backup / dump of the original firmware you hopefully did before flashing something? Attach or post those images. What machine / board are we talking about?

That what I’m worried about, they might outright scam myself/my parents

So could you tell me what’s wrong, aside from the obvious one (I’ve been well researched about this, though there’s still some foggy stuff)

Yeah (though it seems that technician don’t actually have the programmer himself)

And again, please answer my original question

I’m not not a teacher, this is basic knowledge, you might search and read yourself.