Downgrade Steps (From L to KK)
1. Download the downgrade tool: UL-ASUS_T00F-TW-5.3.3.3-user.zip/UL-ASUS_T00F-TW-5.2.2.2-user.zip
2. Using MTP connecting ZenFone5 with PC. (Enable MTP: Setting-->Storage-->press the USB icon on right corner--> Enable MTP)
3. Copy file UL-ASUS_T00F-TW-5.3.3.3-user.zip to t he ZenFone5 internal storage.
4. Remove the USB cable, the device will pops up the system upgrade information.
5. After finished, device will auto reboot and perform factory reset.
6. Then copy file UL-ASUS_T00F-TW-5.2.2.2-user to the ZenFone5 internal storage again.
7. After downgraded, device will auto reboot and perform factory reset.
8. After finished, please go to Settings->About-> software information->Build number. The version should be V2.21.40.44