[Android Q&A, Help & Troubleshooting] MurVur:
I am very new to the subject, trying to understand the concept of flashing ROM and related subjects about Android.

In previous years, for our small business for the staff we purchased 9-10 cheap Chinese phones (Blackview brand, MediaTek MT6580). By the time most of them became unusable (stuck in boot logo, bootloop, or never responding to power button etc.

Now a days I start learning these subjects and tried to fix them. By reading many pages and testing different ways, until now, I rescued 5 phones (BlackView A7) by the help of Stock ROMs & flashing them with SP Flash Tool.

There are 3 more phones (2 Blackview A7 and 1 Blackview A30) , although I tried a lot, and successfully flashed with different ROM releases I could not change any little thing on them! (Maybe this is "hard brick" as what they call)

In last 5-6 days by reading and by practicing I could understand and learn a lot of new things about Android world.

But there is one point I STILL CANNOT understand anything about it!

And I could not find any little explanation on the web also! (This is what I write in my title).

Below, I will try to explain in which point exactly I am confused;

As I understand when phone is turned off we can reach to flash memory from USB connection (and plus a tool like SP Flash Tool), where the all partitions (including boot, kernel and all critical information is written and stored) of the phone. If this is the case, then it means we already have the power of controlling everything on the phone BIT by BIT. Isn't it?

But when I look to the practice the things are not going parallel to this.

People mostly focused on different controlling mechanisms like unlocking bootloader from fastboot, installing custom recovery to root and to get a full backup etc.

But in my understanding if we can reach to the Whole Memory (for reading and for writing) then getting a Whole Backup and Restoring it must be as easy as reading whole flash bit by bit (or by sectors etc. as how it is called) and storing them in an image file.

And for restoring, writing(flashing) back it again to the flash memory trough USB connection when the phone is off. (But there is no method like this in real practice???)

Or, another example; Why don't we have 2 kind of bootloader image (.img) files, one of them original (locked) and one of them modified (unlocked). When ever we need to unlock the phone, why are not we simply flash that part (or partition) of the flash memory with modified .img file and solve the issues easily? (As I see nobody is applying or advising this king of way)

My understanding and real world solutions are very different!

So it means I am making a mistake in understanding. I am coming to this point. But I cannot know exactly what I am understanding wrong.

Actually I want the know where, in which point I am thinking the subject in the wrong way?

For example, by using SP Flash Tool can we reach and write(flash) only some limited part of the flash memory? Is it because of that?

Or, is some information (eg. bootloader code) written in another unreachable part of the phone except flash memory? Can it be the reason?

And one last example from my case, my Blackview A30 phone keeps booting again and again. Just after showing boot logo some seconds it restarts all the time.

I installed many different of ROMs successfully, but this behavior NEVER changed.

And then I formatted all flash but not flashed any ROM after that for trying and seeing the reaction of the phone. It was same again with the same boot logo.

So I am thinking; Isn't this boot instructions and logo also written in the flash memory? If I format everything there this phone must be without any action when I press power key?

How can it do the exactly same action? Then what did I format?.

They are saying "A soft brick is usually caused by a dirty flash. This can be fixed by flashing the original rom. A hard brick means that your phone is as good as dead.".

For fixing hard brick which other parts of the phone professional are reaching and re-wrting ?

What cannot we reach/change on the phone by flashing ROM ? and what we must reach and write more to have the full control in all bits of the system?

A clear explanation of this concept will clarify many things in my mind, because I am stucked in this subject because of not understanding this point.

Thanks in advanced.