What can brick a Sony Smartphone?

[Kaffeetrinker]

Hey!

I want to start developing on an old Sony smartphone, the Xperia Miro st23i (Mesona).

Why this device? It isn't expensive to buy a new mainboard in case I break it and for reasons of sentimentality
I have already compiled kernels for Desktop Linux for various reasons.

Now to my question:

There are CM10 sources and some 2.5-ish TWRP available which I intended to upgrade.

Can I break access to fastboot by flashing a kernel that doesn't work at all?
This always happens every now and then when trying something. But on my Thinkpad, I could always swap the hdd when I've messed things totally up... Here, I can't do that.

Same question for TWRP, can I break fastboot?

Can a messed up partition layout break fastboot?

How could I break fastboot?

I think my questions applies to more or less every Sony phone.

I couldn't find any information useful to me by Google or Xda search because the results are so full of questions how to get into fastboot...
I absolutely don't know how the fastboot mode works and what it depends on.

I just want to know what major mistakes I could do before I do them. Maybe I can prevent to be in need of a JTAG Interface by asking in advance

Thanks for any useful answer!



PS: Please don't discuss the fact I'm gonna develop on this device. The amount of thanks given in case I'm successful will be like 4 and the device will be sluggish as hell on Marshmallow or Nougat because it has only a few MBs of RAM and only 1GHz CPU. I know that! But I don't want to start developing on a device that's so expensive that I can't afford to break it.
You wouldn't let a newbie "try to learn something" at your new Prius. You would give him your old 1992 car that you don't need anyway, regardless of its top speed -

 

[hypertrack]

Hey!

I want to start developing on an old Sony smartphone, the Xperia Miro st23i (Mesona).

Why this device? It isn't expensive to buy a new mainboard in case I break it and for reasons of sentimentality
I have already compiled kernels for Desktop Linux for various reasons.

Now to my question:

There are CM10 sources and some 2.5-ish TWRP available which I intended to upgrade.

Can I break access to fastboot by flashing a kernel that doesn't work at all?
This always happens every now and then when trying something. But on my Thinkpad, I could always swap the hdd when I've messed things totally up... Here, I can't do that.

Same question for TWRP, can I break fastboot?

Can a messed up partition layout break fastboot?

How could I break fastboot?

I think my questions applies to more or less every Sony phone.

I couldn't find any information useful to me by Google or Xda search because the results are so full of questions how to get into fastboot...
I absolutely don't know how the fastboot mode works and what it depends on.

I just want to know what major mistakes I could do before I do them. Maybe I can prevent to be in need of a JTAG Interface by asking in advance

Thanks for any useful answer!



PS: Please don't discuss the fact I'm gonna develop on this device. The amount of thanks given in case I'm successful will be like 4 and the device will be sluggish as hell on Marshmallow or Nougat because it has only a few MBs of RAM and only 1GHz CPU. I know that! But I don't want to start developing on a device that's so expensive that I can't afford to break it.
You wouldn't let a newbie "try to learn something" at your new Prius. You would give him your old 1992 car that you don't need anyway, regardless of its top speed -

Sony devices can use flashtool which is different from fastboot and provides the ability to reflash the full firmware - which helps you get out of most issues you may encounter.

 

[Kaffeetrinker]

Sony devices can use flashtool which is different from fastboot and provides the ability to reflash the full firmware - which helps you get out of most issues you may encounter.

Thanks for trying to answer my question, but that's not it.
I've already unbricked like 50 phones by exactly following tutorials and reading everything I could find.

In the end, I just want to know what flashmode or fastboot mode depend on. I want to know which partitions I may mess up and which I may not mess up.

My guess is I may do everything as long as I don't reflash the bootloader partition.

 

[hypertrack]

Thanks for trying to answer my question, but that's not it.
I've already unbricked like 50 phones by exactly following tutorials and reading everything I could find.

In the end, I just want to know what flashmode or fastboot mode depend on. I want to know which partitions I may mess up and which I may not mess up.

My guess is I may do everything as long as I don't reflash the bootloader partition.

Ahh ok - so I bet @Bin4ry would be able to answer that question - either him or @Androxyde

 

[SkandaH]

@Kaffeetrinker

This thread by @munjeni used to contain much more detailed info about the S1 bootloader, but most of it can't be accessed right now.

 

[Kaffeetrinker]

@Kaffeetrinker

This thread by @munjeni used to contain much more detailed info about the S1 bootloader, but most of it can't be accessed right now.

Thank you very much! This thread gave me some words to google. Doing so, I found the information I needed

As soon as summer's over, the project can start.

To answer my own question in short: you can't hardbrick a Sony device as long as you don't mess with the bootloader.

Fota recoveries are completely seperated from the actual ROM (although they can be updated together).

Fastboot does neither rely on Fota kernel nor does it on the system kernel.

As long as you do only regular rom developing and don't change the partition layout or mess in any other way with the bootloader partition, nothing should go wrong.

If you create an unbootable system kernel, you still can use your twrp. And if you create an unbootable TWRP, you can still get into the system.
If you mess up both, you still habe got fastboot.