[LeEco Le Pro3 Guides, News, & Discussion] slgooding:
You may find that you need to return to stock/locked bootloader for various reasons. You can find how to do this by digging throughout various threads on this forum. decided to simplify things and bring it together in a single thread. After restoring you will be able to do OTA updates as well.

FLASHING FACTORY 5.8.019S

STEP 1: Download the backup

-- Source Thread: https://xdaforums.com/le-pro3/how-to/le-pro-3-lex727-twrp-backup-eui-5-8-019s-t3504761

-- FILE: https://drive.google.com/file/d/0B5xyvHc4wgEVWHFKMWZqLWEyTTg/view?usp=sharing

Note: There is a TWRP backup for 20s currently on this forum. I do not recommend using it. Many have had issues booting after restoring it (me included).

STEP 2: Setup TWRP Backup Directory

If you download it to your PC use adb to push it to your device. You should have an existing directory within /sdcard/TWRP/BACKUPS/ that holds your backups. I believe the directory is your device id.

If the directory does not exist, you need to get the info from your device.

Run adb devices

It will be the hash listed by your device. Make a directory in TWRP/BACKUPS/ with the device id. Mine is "6293eaef".

For example, any backups that I want to restore to my device from TWRP need to be located in a sub-directory within: /sdcard/TWRP/BACKUPS/6293eaef/

At that point you should have the directory you need to copy the backup into.

STEP 2: Copy the Backup (originally named TWRP.zip) to /sdcard/TWRP/BACKUPS/6293eaef/stock

Do the following if you downloaded it to your computer:

adb push TWRP.zip /sdcard/TWRP/BACKUPS/DEVICE_ID/stock/
adb shell
cd /sdcard/TWRP/BACKUPS/DEVICE_ID/stock/
unzip TWRP.zip

If you downloaded to your device, you just need to move the zip file to the TWRP backups directory and extract it.

STEP 3: Restore in TWRP

Boot into TWRP recovery (if not already there).

adb reboot recovery

OR

hold volume up and press power button

RESTORE the backup.

I selected everything. This will install default recovery and remove TWRP.

Do a FULL wipe AFTER flashing. Be sure to wipe the data partition to clear any encryption.

[OPTIONAL] RESTORE LOCKED BOOTLOADER X727

This should not be necessary for X720 devices because the bootloader comes unlocked. I would only suggest re-locking if you need to return your device for warranty support.

To lock the bootloader you need to flash emmc_appsboot.mbn and xbl.elf from an OTA

Step 1: Get 5.8.020s OTA

-- File: https://www.androidfilehost.com/?fid=457095661767124419

After downloading extract 5.8.020S_sta.zip.

Inside the firmware-update folder are 2 files: xbl.elf, and emmc_appsboot.mbn. You need to flash both of these files in the bootloader to relock it.

Step 2: Boot to fastboot

adb reboot bootloader

OR

From power off, hold volume down and then press the power button.

Step 3: Flash stock bootloader from OTA zip

Run the following commands while in the firmware-update folder you extracted from 5.8.020S_sta.zip

fastboot flash xbl xbl.elf
fastboot flash aboot emmc_appsboot.mbn

The bootloader is now locked again.

Run

fastboot reboot bootloader

and then

fastboot oem device-info

to verify.

NOTE: I found that after using this method to re-lock the bootloader I could no longer use the guide for persistent bootloader unlocking.

If you want to unlock the bootloader again later, you need to manually flash the emmc_appsboot.mbn from the file in this thread:

https://xdaforums.com/le-pro3/development/x727-model-persistent-bootloader-unlock-t3500388

FILE: https://www.androidfilehost.com/?fid=313042859668275431

I hope that some of you find this helpful. Please let me know if there is any additional information that I should add to this thread. I will update it as needed.

Cheers!