After having stayed away from the Asus Zenfone for a while, it's now time to get back and give it the much awaited update. For me, after rooting it wasn't possible to update the Zenfone via OTA. So I had to sideload the update. If you are facing the same issue then I would recommend following the steps below. Keep in mind, you will lose all your apps and settings. What are you waiting for?! Dive!! Dive!! Dive!!
BUT WAIT!!
As always, the risk is yours to take and yours alone!! I am not responsible for any damage caused.
Things to NOTE before proceeding with the download
Your Recovery Image and Fastboot Image should match the firmware you are going to flash
For example: If your OS firmware version is WW_3.23.40.60 then your Recovery and Fastboot images should also have the corresponding number and SKU.
Take my example for instance. My OS Firmware was WW_3.23.40.60, so the Recovery and Fastboot images I had to download were 3.23.40.60_ww_recovery.img and 3.23.40.60_ww_fastboot.img.
How to identify which SKU your Zenfone belongs to
Settings > About > Software Version – See the build number
XXX_T00X_WW_XXX_2.19.40.18.XXXXX
Make sure you download the right SKU package to root the Zenfone; else you might end up bricking the phone. WW for WW based versions, CHT for CHT based versions, TW for TW based versions.
Tools you will need
Asus Lollipop firmware for:
To make the ADB extraction process a little simpler, I have uploaded the files here. You will only need adb.7z. Download it!
Follow the steps carefully
1. Keep all files under one folder
2. Install the ADB Driver
3. Install the Intel USB driver
4. Reboot
5. Extract the adb.7z file (I recommend using 7-Zip)
6. Copy the Recovery image, Fastboot image, and OS firmware to the ADB folder
7. Enable Developer Options: Settings > About > Software Information > Rapid tap on “Build Number” (Approx. 7 times)
8. Enable USB Debugging: Settings > Developer Options > Check “USB Debugging”
9. Connect your phone to PC and confirm the RSA security pop-up (Check “Always Allow”)
10. Head into the ADB folder. Keeping Shift pressed, right click within the folder (empty space) and choose “Open Command Prompt Here”
11. Type “adb devices” to see if your phone is connected (reinstall the drivers if nothing gets displayed)
12. Type “adb reboot bootloader” followed by “Enter”
13. Once your phone has re-booted into the Bootloader, type “fastboot flash recovery <recovery name.img>” You can skip typing the whole name by hitting TAB. “Enter” Make sure you flash the right image
14. Type “fastboot flash fastboot <fastboot name.img>.” “Enter”
15. Choose boot to recovery by navigating through the menu using the volume up/down keys. Use the power button to select
Don’t panic if you see a dead DRIOD with “No command” displayed.
18. Switch back to your Command prompt and type “adb sideload <OS firmware name.zip>”.
19. Once the update process is complete, choose and select the following options: wipe cache partition followed by wipe data/factory reset.
The entire process takes a while. So, please have some patience. Rebooting or switching off the phone will lead to a BRICKED or DEAD phone.
20. Select “Reboot system now” when the entire process is over. Again, have a little patience till it boots into Lollipop.
