[HTC Desire S] Rostwildch:
FIRST OF ALL:

These steps are NOT official/universal, these steps worked for me, and I followed several steps form several threads. READ them (bottom of this post) entirely to be sure you can do it without problems, and to be sure how to do it (use of fastboot, adb, etc...)

Also, here is only explained for Europe, search the proper files for other parts of the world.

Story:

I wanted to revert to stock my phone, so I followed this thread instructions:

http://xdaforums.com/showthread.php?t=1460713

I downloaded the RUU_Saga_Europe_1.28..., I followed the thread that used "Android Flash" system. Opened it, selected engHBootOverARX.img, select "actually in fastboot" and Android Flash did its work, flashed the hboot.

Then I started RUU. In the middle of the process it gave me the "Wrong Bootloader Error" and closed. Now my phone is S-ON, HBoot 0.98.0000, I can only load fastboot.

I posted a question here hoping somebody help me.

Solution:

Ok guys, if you are in this situation, dont panic as I did, surely the way I solved this could help you.

If you tried the above, and now you are stuck on bootloader like this:

HBOOT 0.98.0000 (or .0002)

S-ON

fastboot.exe getvar version-main gives 12.10.401.5 (or so)

and RUU wont let you actualize your phone.

I did the following:

1) First of all I needed to upgrade the hboot. Since I had no adb nor recovery, I had to do it via fastboot. In order to do that I needed an hboot that comes algon a higher version than 12.xx..., otherwise it wouldnt let me flash it... In thread [1] there is a .zip OTA in post number 41 (thanks to chargetw) with an IP dir. Download it, and get the firmware.zip from inside. Now I had to flash that firmware from fastboot, in thread [1] jneapan explain how to flash it:

example:

fastboot.exe erase cache

fastboot.exe oem rebootRUU

fastboot.exe flash zip path\to\firmware.zip

2) Ok, I noticed the 2.00.0000 (or .0002) hboot version in fastboot. From here, I could go thru the HTCDev.com solution to unlock the bootloader. Easy steps flashing an auto-generated email-sended Unlock_code.bin, you will understand it when you get thru it.

3) Nice, I had an unlocked bootloader, I could flash a custom recovery. Choose one (I used [2], but you can use the one that you prefer). And flashed it with fastboot:

example:

fastboot.exe flash recovery path\to\custom\recovery.img

4) Once I had the custom recovery, it gave me several errors when trying to mount /cache. At first my heart stopped for a while, but then I read thread [3]. I followed that thread and noticed that the "dmesg | grep mmc0" command gave me no error, so I followed step 2 form that thread to restore my cache partition.

5) Then, I could flash safely any custom ROM. I chose a prerooted stock one. Search [4] for one of your like, flash whatever you want.

6) Aafter all that things, I wanted to get my phone reverted to stock, so I needed to use a RUU. Unfortunately, all RUUs gave me a bootloader version errors because my main-version was then 13.xx... In order to do that I followed the misc_version steps form [5]. Since my ROM was already rooted, I only followed step 2 from that thread's first post, then the step 5 to relock the bootloader, and finally the step 6.

After all this, the RUU finally finished installing, and now I have a complete stock ROM.

Thanks in first place to foX2delta for his fast response. Couldnt make it without him :)

Thanks to all the listed threads participants. Without reading their wiseness surely I would be with a stoneage phone.

Last of all thanks to the entire xda community, for letting this forums being the best of the world :)

Final words:

I have learned a thing: NEVER, EVER, follow the steps of ANY GUIDE (included THIS) without reading EVERYTHING very carefully. One bad thing and BOM!, you are screwed.

Threads list:

[1] http://xdaforums.com/showthread.php?t=1412398

[2] http://xdaforums.com/showthread.php?t=1484753

[3] http://xdaforums.com/showthread.php?t=1284196

[4] http://xdaforums.com/showthread.php?t=1146601

[5] http://xdaforums.com/showthread.php?t=1318919