Download LeEco Letv LE Max 2 X821 official stock firmware from the link here, and follow the provided flashing instructions to learn how to flash the stock rom.
If you notice that any of the links provided below is broken or doesn’t work, please post in comments section so we fix and update it ASAP.
How to flash
Step 1: Rename the downloaded zip file to update.zip, and copy it to the root directory of your Device Internal storage.
Step 2: Open the Phone “File Manager” and click the firmware “update.zip” to upgrade Phone firmware.
Step 3: Select “Update” option on the next screen.
Step 1: Download and rename file to update.zip
Step 2: Copy to the root of your internal storage
Step 3: Reboot to recovery mode
Step 4: Select install update from sdcard
Step 5: Wait for the flashing process to complete
Step 6: Reboot phone normally. Done!