HTC One firmware in fastboot

As I "autogenous, through the back, glands cut out"

How it all began

It all began quite prosaically. The HTC One phone brought out a message that it cannot charge in Host mode ... I brought it and brought it out, as I did, so I removed it, without giving it any meaning, but in vain! When the battery charge began to run low, the phone was connected to the USB cable and ... nothing happened ... at all, that is, the reaction was zero ...
I went to Google ... there were found a couple of tips on launching in different modes with different combinations of buttons. The tips did not help, but it turned out that in the “fastboot” mode, the phone is visible via USB. Here it was decided to "flash" ... And so it began ...

They told me to back up "our ALL"

Since access to the phone via USB only in fastboot mode, then the back up was not made, but all the sections of the internal memory that were reached were formatted ... But, in order:

• Unlocked the device ( detailed instructions here )
• Filled recovery from TWRP
• Filled, via bluetooth, USB, it does not work, on the device an alternative firmware from CyanogenMod
• It did not help ... USB only in fastboot, as it was, it remains
• !!! Rubbing all sections to which TWRP could reach !!!
• Restarted and ... voila ... the "brick" without an operating system is obvious ...

And everything would be fine if it were not for one “BUT”. USB only works in fastboot, that is, you can now upload something to the device only in fastboot, here it is the joy of a candy bar without an external flash card. And then the second ambush: the S_ON key, which does not allow you to upload earlier versions or change the HBOOT.

Searching of decisions

The most correct in this situation, in my opinion, would be the use of the ROM Upgrade Utility (RUU) utility, but, either I was looking badly, or HTC was hiding so well, but I couldn’t find a “fresh” version of RUU ... It’s a pity the thought continues to work.
The fastboot utility allows you to upload an image file to some sections, including the system section. But where to get the image of the system section. The search for the finished result is not brought. There was a thought to make a partition from the system folder of the zip file with the firmware.
On the forum I found a way to get a file with an image, an experimentally obtained algorithm for creating the “right”, from the point of view of HTC, image and ...

Small retreat

There were two problems:

1. Or I did not understand something from the description or one of the two, but in order to get the “correct” image, it was necessary to first create it with the make_ext4fs utility, and then convert it with the simg2imgu utility
2. The size of the image uploaded using the fastboot utility is limited, somewhere in the region of just over one gigabyte

We continue to "use autogen"

Due to the size limit of the image, I had to cut the system folder from the stock firmware a little.
After uploading the resulting image with the system, the device started, not without “glitches”, but the main goal was achieved - it became possible to use Bluetooth (USB only in fastboot mode)
Using Bluetooth to transfer files the size of around a gigabyte, still that ... pleasure ... After the third interruption of the transfer almost at the very end of the file, the thought accelerated and ...

And here are the glands.

And so we have:

• With the help of the fastboot utility, we can fill in the system section with some image
• Image is a set of files
• TWRP can mount the system partition and manipulate files from it

It is necessary:

• Pour zip file with firmware to the internal memory of the phone

Problem:

• USB works only in fastboot mode

Decision:

• Create an image containing only a file with firmware (due to image size limitations, the firmware from CyanogenMod was chosen)
• Fill the resulting image into the system section with the fastboot utility
• In TWRP, we mount the system partition and transfer the zip file with the firmware to the user zone from it (/ sdcard / download for example)
• In TWRP, we flash the device

HOORAY!!! Earned ... not all ... USB continues to "fail", but sometimes it turns on ...
After all these adventures, the device was returned to the stock firmware, but that's another story, the main thing that worked.