[Sony Xperia Z Ultra] I.T.:
Hi,

Anyone could help me with a weird behavior of Xperia Z Ultra of my sister?

THE PROBLEM:

- Trying to power it on, it boots up and stuck on "Sony Xperia" logo with no notification led sinalization.

- Once stucked on "Sony Xperia" logo, there is no response from pushing any combination of buttons ("POWER"; or "VOLUME_UP" + "POWER"; or "VOLUME_DOWN" + "POWER"). It is only possible to power it off pushing (and waiting for 3 vibrations) the red button besides the microSD card slot.

- Once powered it off, recharge is possible pluging it to the wall charger, the red led keeps solid until around 90% and then the notification led turns solid green and keeps charging until 100%. (It is possible to see the battery charge icon briefly pushing the "POWER" button).

My sister says that she has never did a system update, so it may have the stock firmware and locked boot loader; and this problem occurred few weeks after the end of the warranty during normal operation at low battery charge... when suddenly self powered off by battery discharge; after that, she plugged it at wall charger and tried to power it on, but everytime it keeps stucked on "Sony Xperia" logo since then.

MODEL IDENTIFICATION

On a stick at its box says:

Model: C6843 / Xperia Z Ultra

SI 1276-0910.12 PB

FIX TRY 1:

My first try to fix the problem was using the last version of Xperia Companion software in Windows 7 Ultimate SP1. I selected the option "Software Repair" and, following the instructions, connected the device to the USB holding the "VOLUME DOWN" button; the notification led fast blinked once red, and faster blinked once green and then turned off; Windows installed "SOMC Flash Device" driver. Aparently, the device was detected and showed the software version available to repair: 14.6.A.1.236-R3D and the repair process had gone to the end with no errors. But, after disconnected the device from USB and tried to power it on, its behavior keeped unchanged... keeped stucked on "Sony Xperia" logo.

I tried one more time with software repair of Xperia Companion, but this time I connected the device to the USB without holding any button, and for my surprise, it had gone to the end of repair process without errors! It seens like the device stucked in flash mode but without notification led sinalization!

FIX TRY 2:

I downloaded the last version (0.9.22.3) of Flashtool software of Androxyde and the last version of XperiFirm (v5.0.0).

I executed XperiFirm and browsed looking for my model/customization firmware and it showed that it has 3 firmwares for the model C6843, but curiously, there is no firmware available for my local customization SI (CDA) 1276-0910... So, I downloaded both CDA available for my country (Brazil): 1277-0849 and 1277-7513.

Using the Flashtool, I created the bundle and flashed the first (1277-0849) firmware version 14.6.A.1.236_R3D with no errors, but the problem keeped unchanged. I repeated the process with the second (1277-7513) firmware version 14.6.A.1.236_R5D, but with the same results.

Looking at the Flashtool's log, we can see that the device is detected as:

"...

Current device : C6843 - BY900EB69A - 1277-0849_R3D - 1276-7278_14.6.A.1.216 - DTV-LTE_14.6.A.1.216

..."

This is a bit confusing: witch is the CDA of my sister's device? The one on the stick at its box (1276-0910) or one of the log above (1277-0849 or 1276-7278)? I know that it is a DTV device (DTV = Digital TV).... but, anyway... none of the firmwares is fixing the problem.

I've already tried a downgrade: I downloaded a FTF from xda (C6843_14.4.A.0.108_BlueEther.ftf) and sucessfully flashed it, but also did not solve the problem. In this case, the logo at boot loader changes a little (it shows only "Sony", while in the last versions shows "Sony Xperia") proving that the boot loader is being written.

I've repeated all tries using the previous version of Flashtool (0.9.18.6), but with no different results.

As I observed when I using Xperia Companion, the same occurred with Flashtool in all tries: the device seems to be stucked in flash mode without notification led sinalization.

I've already searched xda and google for a solution, I've read lots of pages, I've tried several tips, but with no success.

Anyone have any idea of what I can do to fix the problem? :fingers-crossed:

Thank you.