[General Topics] Danny_Dewet:
ATTENTION: I take no responsibility for any problems you may have. The guide was tested on variant 6/64 (C105-6)

I created this guide especially for the English translation, but also to be as clear as possible. I hope you enjoy it.

Ok lets start!

NOTE: find all the files at the bottom of the thread. Once the conversion is done, you can install any ROM for the LEX720. Under the thread I wrote some ROMs.

STEP 1: Flash TWRP Recovery and Unlock Bootloader (if you have already unlocked the bootloader and installed the twrp recovery skip this step)

1) First go to settings on your device, go to info and press 5 times Build Number to unlock the developer settings

2) Go to Developer settings and active OEM Unlock and USB Debug

3) Now Download the zip TWRP file and unpack it

4) Open CMD from unpacked folder and connect the device on your computer, write this command on your cmd windows and press enter

adb devices

press on always allow usb debugging and press ok

5) Now reboot your device into Fastboot Mode (power button + volume key down)

6) Connect the device on your computer

7) Go to unpacked folder and open cmd

8) Now in order write these commands

fastboot oem unlock-go

fastboot flash recovery recovery.img

fastboot boot recovery.img

Well done, now you have TWRP recovery!

To change the language press on right button and select your language, after go to reboot and press system

STEP 2: Conversion from Cool Changer S1 to LePro 3

1) Reboot your device on Recovery Mode (TWRP) (power button + volume key up)

2) Make a backup of everything including EFS (Optional, just for security, I have not lost the IMEI codes but I still suggest doing this step. And save the Backup folder on your computer, the il folder is called TWRP)

3) Do a Factory Reset go to Wipe and make Format Data, write yes to confirm, after go again to Wipe, Advanced Wipe and do: Dalvik, System, Data and Cache

4) Now connect the device on your computer (from recovery)

5) Donwload the Conversion ROM and put it on your device go to Install and Flash it, after your device will reboot but the system will not start, you will only see the boot logo and a black screen. Do not panic, restart the device in recovery.

STEP 3: Flash Custom ROM

1) Connect your device on your PC from Recovery

2) Before installing a Custom ROM I suggest to update the TWRP recovery because the ROMs like the Lineage OS can not be installed because the installation package does not recognize our device as LEX720, then download the updated IMG file of the TWRP recovery and copy it into the device (always from recovery), go to install > install image and select the IMG file of the TWRP recovery, after go on Reboot and press on Recovery.

3) Download on your PC a ROM you want to install and put it on your device (i have choose Lineage OS)

4) Download on your PC Gapps from OpenGapps Website and put it on your device (download only ARM64, and i suggest the pico package)

5) Now on your recovery go to Wipe and make Format Data, write yes to confirm, after go again to Wipe, Advanced Wipe and do: Dalvik, System, Data and Cache

6) Now go on Advanced > Config Device> Set_Device_zl1, go back, go to Install and choose the ROM that you have downloaded, do the same thing (without set the device to ZL1) for Gapps without do any wipe.

7) Reboot your device and now you have a Custom ROM!

STEP 4 (optional): CPU to 2.15 GHz or 2.35Ghz (Only for Lineage OS Based ROMs and for JUI ROM)

1) Reboot your device on Recovery Mode (TWRP) (power button + volume key up)

2) Make a backup (Optional)

3) Go to install and flash 2.15 GHz or 2.35 GHz (i suggest the 2.15GHz because the 2.35 version is not stable and can cause problems, for Oreo there is only the 2.15Ghz version)

4) Reboot your device, you are done!

ROM I'm using right now: Aosp Extended 5.4 Android Oreo 8.1 with 2.15GHZ kernel, the build I'm using is April 9th, because the 2.15GHz kernel with the latest builds based on the latest Codeworx sources causes data encryption so do not use the kernel until the developer releases an updated kernel!

Link: https://xdaforums.com/le-pro3/development/rom-aospextended-rom-v5-3-t3773016

DOWNLOAD SECTION:

TWRP zip file: https://drive.google.com/file/d/1adnP1g1eX2zIWS28cKTt_rM9o4GyCjL9/view?usp=sharing

Conversion ROM: https://drive.google.com/file/d/0B3mAQUl81LRsU2ZOYjd6TEs0Z2s/view

2.15 GHz Kernel (works only on Lineage OS 7.1.2 or Lineage OS Based ROM): https://drive.google.com/file/d/1q38ouVtH4SGHhoHw0pR816JIga5g-O4F/view?usp=sharing

2.35 GHz Kernel (works only on Lineage OS 7.1.2 or Lineage OS Based ROM): https://drive.google.com/file/d/1bhPXv2fIdn7gKwsh8nTDNojDTgCb559v/view?usp=sharing

2.15 GHz Kernel for Android 8.1 Based Roms (works on: AICP, Pixel Experience etc.): https://drive.google.com/file/d/1UofwwVDTFdfuDDHcyMgwp_FHbTyRU6ki/view?usp=sharing

Gapps: http://opengapps.org/

CUSTOM ROMS SECTION:

-Android 8.1 (use only 8.1 Gapps)

AICP (stable, weekly): http://dwnld.aicp-rom.com/?device=zl1

-Android 7.1

AICP: http://dwnld.aicp-rom.com/?device=zl1

Paranoid: http://get.aospa.co/official/zl1

LineageOS: https://download.lineageos.org/zl1

ResurrectionRemix: https://sourceforge.net/projects/resurrectionremix/files/zl1/

JUI 7.1.1: https://yadi.sk/d/QIujsNyK3RQvrJ

2.15 GHz Kernel for JUI (works only on JUI): https://drive.google.com/file/d/1DjVZ6ZYBfnfYFstUTJwvaKAE2try3Lma/view?usp=sharing

2.35 GHz Kernel JUI (works only on JUI): https://drive.google.com/file/d/1qa5KfVVxVm-PGP-e2eks8Zbf_uy4VZuS/view?usp=sharing

Stock Kernel 1.9 GHz for JUI (works only on JUI): https://drive.google.com/file/d/1dDp71oPETROEYcWF1aMHdX6Zi6IqYaIG/view?usp=sharing

Original Thread (Russian): https://4pda.ru/forum/index.php?showtopic=822330&st=280#entry64605939

Thanks To:

4PDA Forum

Androidiani Forum