[LeEco Le Pro3 Guides, News, & Discussion] tsongming:
You will notice that storage is not accurate so that part has to be fixed first before doing anything else.

You need to perform factory reset your phone and choose the option “Format Virtual SD card”. This resolve the storage issue.

Turn on the phone and follow any prompts for setup and don't forget setting up developer options and clicking OEM unlock as if the phone were original stock after the factory reset, shut off phone.

Download mauronofrios : TOOL ALL IN ONE

>>> https://xdaforums.com/le-pro3/development/tool-tool-one-mauronofrio-t3580611

>>>>>>>>> Use the tool to update your drivers, ADB and set system wide privileges for ADB.

Place the phone into Fastboot mode

Download Most recent versions of Rom ( I would use Lineage this first time )

You will also need the newest version of TWRP

Go to the Lineage 15.1 page and download the recommended versions of your firmware, and Gapps

Download Magisk 16.0

Use the All in One Tool Read the instructions first and ensure its up to date

Manually place the phone is fastboot mode

select your phone from dropdown

Use automated TWRP installation, if it fails, Manually point use All in One to TWRP on your PC

After Flashing Twrp Unplug usb and Reboot your phone into recovery while pressing volume “+” button and power button

TWRP screen, click "Never show this screen during boot again” and “Swipe to Allow Modifications”.

From this point you can reconnect USB drive and Go back to using All in One, ADB or OTG whichever method you are most comfortable using.

Flash your Firmware and Magisk first. If Magisk fails flash your modem file and flash Magisk again, this time it will work.

Reboot to recovery make sure you click checkboxes to ensure TWRP is installed

Install Rom> Add More Zips > Gapps and Magisk again.

Boot to Recovery, Boot to system > Done.

If the above doesn't work try these Alternate Steps,

I forgotten that I posted the steps below a few weeks ago , so I just found that post and copied pasted what I wrote before.

Note: You could also just try these steps first, the key part of getting past this issue is factory resetting first: "Format Virtual SD Card"

Repair Storage

Restore the storage back to default by going to Backup/Restore in Settings and Factory Resetting the Phone with the "Format Virtual SD Card" Option selected.

Next install the latest Official EUI download EUI 21S ( do mot load anything above this)*

Rename the file to Update.zip and place on OTG drive or into phone storage using file manager.

Go to check for update and click hamburger icon in top corner and select you Update.zip file to upgrade

If it doesn’t work retry steps,, If you have an issue from here let me know, also let me know if it works.

Worst Case after restoration attempt to resolve size issue.

if you still have a problem install Twrp and Flash via TWRP install.,*

Wipe EVERYTHING... and flash the ROM using a usb Flash Drive and after mounting USB OTG Storage.*

To Flash TWRP simply shut down the phone and By Keeping the Volume Down Button Pressed Hit the Power Button to Enter the Fastboot Mode.*

Flash TWRP Recovery...*

Boot into TWRP Recovery...*

Restart TWRP Recovery... I

Insert the USB Flash Drive*

Using USB OTG Adapter... and flash the ROM using the Install Tab in TWRP Recovery.