For some reason, you might want to downgrade your HTC One from Android 4.4.2 to Android 4.3. For example, I updated my AT&T HTC One to Android 4.4.2 with Sense 6.0 by converting it to Developer Edition. After using it for some days, I wanted to revert it back to stock conditions. You might want to do it before returning it to AT&T for warranty or other issues. If you just try to flash a lower version RUU, you will most likely get error message. The problem results from the fact that higher Android firmware from HTC usually comes with a higher version of HBOOT. So, whenever you try to flash an RU.exe, it will show you error as it cannot flash a lower version HBOOT to a device which already has a higher HBOOT version. We need to manually flash a lower version HBOOT first and then use RUU.exe to return to complete stock.
Step 1: I am assuming that you have already got your S-OFF and you are on Android 4.4.2 firmware. Most likely, you are on HBOOT 1.57.xxxx. If you are not S-OFF yet, achieve it now. The short steps to achieving S-OFF are:
- Unlock bootloader
- Flash custom recovery and then root your device
- Use RumRunner to get S-OFF. Detailed instructions can be found here.
Step 2: Download the appropriate HBOOT for your device. As I want to go back to stock for my AT&T HTC One, I downloaded the hboot_rumrunner_att_3.17.502.3.zip. Put the file in the same folder as your db and fastboot tools. Now, start your phone in bootloader mode by simultaneously pressing the volume down and power button. Connect your phone to the PC using an USB cable and write the following commands in a command prompt.
fastboot erase cache
fastboot oem rebootRUU
fastboot flash zip hboot_rumrunner_att_3.17.502.3.zip
At this point, your HBOOT will be downgraded from 1.57.xxxx to 1.55.xxxx, which is the same as Android 4.3 stock firmware/RUU.
Step 3: Now that you are in bootloader mode again, execute the RUU_M7_UL_JB43_SENSE50_MR_Cingular_US_3.17.502.3_Radio_4A.19.3263.13_10.38j.1157.04_release_334235_signed_2.exe file. If you don’t already have it, you can download it from http://www.htc1guru.com. Follow the on screen instructions. Your phone should be successfully returned to stock Android 4.3 ROM with Sense 5.0. You can now flash the OTA (described here) to update to Android 4.4.2 with Sense 5.5.