[Xperia Arc Q&A, Help & Troubleshooting] dwengs:
Hello.

I've searched forums and found some threads like this but my problem is a bit like them and a little bit different at the same time.

Sorry for my ENGRISH

I have Sony Ericsson Arc S, (LT18i). My brother bought it from UK and bringed to me, to Türkiye (Turkey). As you guessed, Turkish simcards didn't work and my brother gave money to a mobile phone seller to unlock it's simlock. After this, we able to use phone with Turkish simcards in Turkey.

The other day, after a couple years, I wanted to install a custom ROM on my Arc S.

This is how everything started.

I searched XDA forums and took notes. How can I do it, which programs needed etc.

Preparing

First, I did a factory reset.

After the phone opened, I changed usb connection to MSC, allowed Unknown sources and opened USB debugging.

I installed Flashtool 0.9.10.0. I readed a couple posts about that, previous versions gives no errors.

Under /drivers folder I found a driver package. Installed it with just Flashmode, Fastboot and Sony Ericsson Arc drivers selected.

Pluged in my phone and checked if it's drivers installed or not. Success. I can see my phone in device manager.

Installing

I readed a few guides and they say I have to Unlock bootloader. So I clicked Bootloader Unlock option in Flashtool. Followed the instructions, gone into flashmode, restart, gone into fastmode with pressing menu button and plugging the usb cable etc. There was a window with my IMEI and I followed the instructions and I get a code (long, including letters and numbers) from official sony website. I entered this code to that window and it said my bootloader is unlocked.

After that, I rooted the device. No errors.

Installed CWM via Flashtool. No errors as far as I remember.

AND THIS: Flashing a ROM. I found an Android 5.0.1 ROM and it said that I had to flash boot.img. So I did. I mean, I tried. I GOT ERROR. And, BUM. Something happened and I couldn't open the phone.

After a search, I found a solution says using Sony Companion may restore the phone. I tried this. Follow the instructions and my phone opened with ICS 4.0.4 instead of old version, 2.3. And now, it says, INSERT THE SIM CARD.

I searched the forums about 2 days and didn't find a solution to this. It ignores my sim card. Then, I saw a secret code about simlock and bootloader status and entered that code *#*#7378423#*#*

Under Simlock option,

They say there must be X's. At least the first one must have X on simlock screen but it hasn't. And there are all 0's. No X's, and zeros. So this is bad i think.

Under Configuration

In configuration section, it says Bootloader Unlock Allowed: No. As far as I learned from XDA forums, that means bootloader is locked again. Because it must be unlocked or unlock allowed: yes.

So i tried to unlock bootloader again. I had no idea what I've done. First, it said go flashmode. Done. And it said go into Fastboot. I couldn't. No Blue LED.

You see the thing? => Flashtools says go Fastboot to run Bootloader unlocker. I can't. Forums says I have to bootlocker unlock to enter fastboot. Bootloader unlock to enter fastboot. But enter fastboot to boot unlock. Wow.

Lastly, I tried flashing custom TFT's to see if it can flash or not. IT FLASHED. I can flash STOCK TFT's, even a KERNEL i downloaded from here. I can Root, install Busybox ( I don't know what is it haha), Install CWM 5.0.

But since it can't see my Sim Card, i didn't try to install custom ROM.

What I have to do? How can I unlock to simcard lock if it's locked? is my bootloader locked?

My brain hurts.

I wrote all things because it's easy to solve a problem with more information. So a few things more:

I use Windows 10.

I didn't use original cable at first. But you know, no errors now. It's not important at this point I think.

I unistalled mobile device from devices manager and delete the driver. I installed inf file from sony website and selected it for ADB driver. It says now Sony sa01102 ADB Interface Driver. If Fastboot needs correct drivers, I installed from it's official site, offical one.

I didn't tried another computer because again; no errors from Flashtool.

THANK YOU ALL.

I maybe copy this to other websites.