Restore HTC One X to original ROM My HTC One X came with ICS pre-installed, but then I upgraded it to Android 4.2.2 using CyanogenMod. Now I want to reset my phone to its original ROM, but couldn't find a way to do it.

Someone suggested that I download and run:


  RUU_ENDEAVOR_U_ICS_40_Vodafone_UK_1.26.161.2_Radio_1.1204.90.13_release_251227_signed


but it didn't work. When I run the .exe I get the error:

 Error[155]: UKNOWN ERROR


My bootloader shows its version as:

version-main: 3.14.161.27 
(bootloader) DEBUG: cid: VODAP001
ENDEAVORU PUT SHIP S-ON RL
*** UNLOCKED ***


How can I get the stock ROM reinstalled?
This is a protection that HTC uses to ensure quality in their devices. To re-install their custom stock, you must re-lock your phone. To do this, place your phone into fast-boot mode and plugin in via USB:

At the command line (or wherever you may have the fastboot binary), execute these commands:


  fastboot devices
  fastboot oem lock  


This will lock your bootloader and allow you to run the RUU. Your device should now report "LOCKED". After your device is locked, proceed with running your *.exe on Windows.

(Make sure you're installing the right one first!)
List of RUU's: http://androidfiles.org/ruu/?developer=Endeavor

Full Tutorial: http://androidforums.com/one-s-all-things-root/691874-guide-how-run-ruu-your-htc-one-s.html