[Zenfone 5 Q&A, Help & Troubleshooting] wirleyvaldez:
Find the instructions in dowgrading to kitkat from lollipop and download links from here: https://www.asus.com/Phone/ZenFone_5_A501CG/HelpDesk_Download/

Version WW_5.3.3.3 (Downgrad Version)

Description	ASUS ZenFone 5(A500CG/A501CG) downgrade SOP (Downgrade from L to KK), V2.21.40.44 Only for WW SKU*

Notice:

1. Please must to download the UL-ASUS_T00F-TW-5.3.3.3-user.zip/UL-ASUS_T00F-TW-5.2.2.2-user.zip to perform downgrade procedure.

2. Only apply to same SKU update, Example: WW->WW, CN->CN, TW->TW.

3. Software update cannot transfer the software SKU and downgrade the software version.

4. Downgrade image will only revert back to latest KK version

5. After OTA downgrade, device will perform factory reset automatically.then reboot automatically to complete upgrade process

6. System upgrade may cause part of data missing, please buckup your important data before system upgrade

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

File Size	720.15 MBytesupdate 2015/06/03

Download from	Global

Version WW_5.2.2.2 (Downgrad Version)

Description	ASUS ZenFone 5(A500CG/A501CG) downgrade SOP (Downgrade from L to KK), V2.21.40.44 Only for WW SKU*

Notice:

1. Please must to download the UL-ASUS_T00F-TW-5.3.3.3-user.zip/UL-ASUS_T00F-TW-5.2.2.2-user.zip to perform downgrade procedure.

2. Only apply to same SKU update, Example: WW->WW, CN->CN, TW->TW.

3. Software update cannot transfer the software SKU and downgrade the software version.

4. Downgrade image will only revert back to latest KK version

5. After OTA downgrade, device will perform factory reset automatically.then reboot automatically to complete upgrade process

6. System upgrade may cause part of data missing, please buckup your important data before system upgrade

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

File Size	730.49 MBytesupdate 2015/06/03

Download from	Global