How to downgrade from 1.23, 1.27 hboot S ON

first you will have to find the same RUU that you used to upgrade to 1.23/1.27. Next we will have to brick the device, but in a special way


remove the back cover of the phone and plug it in usb. you must have direct access to the battery, because you will have to pull it out QUICKLY!get your hands on it and be ready

export the rom.zip from the RUU, or the firmware.zip from the 1.27 OTA
and get it in the same directory with fastboot
open up a terminal and go to adb. next:
adb reboot-bootloader
fastboot oem rebootRUU
fastboot flash zip firmware.zip
(example with the 1.27 firmware here)

Once you press enter you will see lines of code like this:

dex@unbrick:~$ fastboot flash zip PG58IMG.zip
sending 'zip' (409063 KB)... OKAY
writing 'zip'... INFOadopting the signature contained in this image...
INFOsignature checking...
INFOzip header checking...
INFOzip info parsing...
INFOchecking model ID...
INFOchecking custom ID...
INFOchecking main version...
INFOchecking hboot version...
INFOstart image[hboot] unzipping for pre-update check...
INFOstart image[hboot] unzipping & flushing...
INFO[RUU]UZ,hboot,0
INFO[RUU]UZ,hboot,100
INFOsignature checking...
INFO[RUU]WP,hboot,0

now you must pull the battery out and interrupt the procedure as soon as this^^ line appears (INFO[RUU]WP,hboot,0). It is going to be very fast, so you have less than a second. be prepared. if you are too late and this line shows up:

INFO[RUU]WP,hboot,100

then let it finish normally and retry. If you do everything correctly, the phone will refuse to boot after a reboot. now you can use the unbrick guide

happy bricking and unricking
Dexter93