[Sony Cross-Device General] dragonator4:
Xperia U Recovered!!!

My phone recovered, I think. :)

I managed to flash successfully in flashmode (I have a locked bootloader). Now charging in low battery mode. I can only hope that it will boot into offline charging mode soon. :fingers-crossed:

Edit 1: -

Yes, I have my phone back!!!! :victory:

Edit 2: -

Here's what happened.

1. I did a full system wipe using CWM, because I wanted a clean install.

2. The drivers were already installed, but I installed them using flashtool (version 0.90). This is what caused the problem.

3. I tried to flash using flashtool, but the connection with my computer in flashmode was not stable. I now believe it was because of driver conflict.

4. Flashing was aborted at kernel because my phone disconnected. This corrupted the kernel and my phone was stuck at the SONY logo, and would not go anywhere. I could only turn it on, not off. No button presses would bring a response, even Volume up + power button did nothing.

5. In my ignorance, I removed the battery, causing the problem to worsen.

6. Then, whenever I connected, whether to computer or to wall charger, the left led (in the illumination bar) used to light up green, like entering flashmode, and then would hang up at SONY logo. In fact, even when I used the power button to power on the phone, the led would flash green. I could not get it into flashmode.

7. I found this guide and let the battery drain out completely. Then I tried to charge it back, hoping to see offline charging screen. But, the phone would display the SONY logo and hang there, without going further. I thought I was dealing with a hard brick, but the fact that I could power my phone on (though not off) and that I could get fastboot, kept me going.

8. I used this software: NirSoft USBDeview (version 2.22) to view all the installed drivers of offline devices.

9. Using USBDeview I removed the drivers and its copies pertinent to my phone.

10. I tried connecting in flashmode, with no luck. I thought the problem was the flashtool drivers, not the driver conflict. So I was using SEUS and not flashtool. Since I could not connect in flashmode, SEUS was useless.

11. I went back to flashtool. I prepared it, and plugged my phone it. Flashing was aborted due to missing drivers. I thought that windows will install the drivers automatically (this was the thought that led me to believe SEUS will work).

12. I tried to install drivers from Sony developer website (still believing that the flashtool drivers were faulty). But it did not come with an exe file, and since I had uninstalled the drivers, I could not replace the existing drivers with these.

13. I again went back to flashtool drivers. I installed the drivers from flashtool, thinking that I will replace them with the drivers from Sony developer website (because I believed that flashtool drivers were somehow corrupted).

14. For some odd reason, I decided against replacing flashtool drivers. I prepared flashtool, plugged my phone in, and saw in amazement and happiness as flashtool completed flashing without any hiccups.

15. I unplugged the phone, and let it charge at the wall charger. It was charging in the low battery mode, with only the red led. Presently, it started normally and I have it back now!!!

Flashtool is the best!