Exynos8890 Recovery - Re-flashing SBOOT via exynos-usbdl Mode

Galaxy S7 / S7 Edge Exynos8890 Bootloader recovery/unbrick through exynos-usbdl

Description

• Exynos devices support a flash mode caled "exynos-usbdl" which is triggered when Main Stage (UFS) Boot fails, a common scenario to fall into this mode is a bad bootloader flash (sboot.bin or cm.bin) or UFS Damage. these files will help you Recovery from that mode and "Unbrick" your phone aslong as the UFS Chip is NOT actually damaged.

• So basically this post is about Attempting to unbrick bootloader on Galaxy S7 and S7 Edge Exynos8890.

• Only Tested on G930F and G935F - Other variant binaries are not tested

• Also a way to document everything i can find about this mode and the various ways to recover from it.

• This is NOT a bulletproof un-bricker on Windows, sometimes re-enumurating / re-connecting to the device fails and causes the 4th binary to not be flashed, Trial and error is needed

• Recommended : A linux computer to run fredric exynos-usbdl flasher instead of MultiDownloader

Requirments to qualify for this Unbrick

There are few things to tell if you are in USB-DL. here are my observations . All of them need to be met to be able to use this repo :

• Your phone does not show LPM (Powered off charging) when plugged to AC outlet

• Your phone does NOT boot to either OS / Bootloader or Recovery (even when performing BL Combo Power + Vol Down + Home)

• Your device is detected for one second only on a windows machine once plugged via USB

• And most importantly Holding POWER button Will allow the phone to be detected in Windows Device Manager

• When inspecting devices in Device Manager while the POWER Button is held, Exynos8890 will show up in devices.

Supported Devies and binary version

• SM-G930F - G930FXXU8EVH2
• SM-G935F - G935FXXU8EVH3
• SM-N935F - N935FXXU8CVG2 [ Un-tested ]

• Other devices can be supported by finding proper offsets, if/when i find information on how to calculate said offsets i will update this

Boring Details

• on Windows we can use a tool called "MultiDownloader" + "ImageWriterUSBDriver_1113_00" to flash in usbdl mode
• exynos-usbdl is a tool created by @frederic as part of an s-boot exploit, However we can use it to recovery from usb-dl much more consistently than windows, see exynos-usbdl
• The Tool is old and drivers originate from Motorolla-BlankFlash which are mirrored here
• SBOOT.BIN is made of multiple binaries at different offsets, split-sboot-8890 was used to strip them out of the SBOOT.BIN binary.
• Currently only SM-G930F And SM-G935F are tested. it should be possible to split other variant's S-BOOT.BIN to use with this guide.
• No, Downgrading BOOTLOADER Version likely does not work due to the rollback bit. the binaries in this post are most recent Rev 8 binaries

Credits and sources

• @frederic for their exynos-usbdl project and research

• https://fredericb.info/2020/06/exynos-usbdl-unsigned-code-loader-for-exynos-bootrom.html

• https://github.com/frederic/exynos-usbdl

• @jeykul for bricking their G930F to test

• https://github.com/astarasikov/exynos9610-usb-emergency-recovery

• https://forum.xda-developers.com/t/guide-repair-hard-bricked-devices-with-deleted-bootloader-sboot.3573865/

Linux Instructions

• If your phone is actually stuck in USB-DL and has no hardware Fault, Then the recovery is as follows :

1- Download this repo as a zip or use git clone https://github.com/ananjaser1211/exynos8890-exynos-usbdl-recovery

2- Open a linux terminal window in the downloaded folder, or cd exynos8890-exynos-usbdl-recovery

3- Plug your device via USB.

4- Execute the recovery script as root sudo ./exynos-usbdl-recover.sh

5- Select your device from the window and hit enter.

6- The script will perform few checks and then Flashing process will start.

7- Once it says Start Flashing hold the POWER Key and keep it held.

8- if you get Error: cannot open device 04e8:1234 that means your device is not in USBL-DL or you did not hold the powerkey long enough.

9- if everything goes well, Your device will reboot into Download Mode once it is successful.

10- you can download your stock firmware from SamLoader / SamFW and follow various other guides online on how to flash your phone via ODIN Or heimdall

• Reference Video of usb-dl courtusy of @jeykul

video_2023-04-25_19-00-33.mp4

Windows Instructions

** Note : Try to use Linux version instead as Multidownloader fails alot at the last step **

• If your phone is actually stuck in USB-DL and has no hardware Fault, Then the recovery is as follows :

1- Download the attached Binaries from Here or the source here

2- Download this reposity as a ZIP and extract it

3- Install ImageWriterUSBDriver_1113_00.exe Drivers

4- Lunch Multidownloader_64bit_1.4.1.exe

5- Press the 3 Dots and select the appropriate config for your device. exynos-usbdl_g930f.cfg etc.

6- Plug your device

7- Hold the POWER Key and confirm your device is detected by checking Device Manager

8- Your Device should show up in multidownloader

• Note : Throughout this entire process, the power button MUST BE HELD otherwise you leave usb-dl mode

9- Press Start and wait, flash takes few seconds. keep the POWER button held at all times

10- It will fail the first 2/3 times, Repeat the process by starting again

• Images from My SM-G935F for reference - First two flashes Faild, 3rd one was succesful (Note : It wont show last stage) and wont mention Write failed

11- Once your phone stays connected while releasing the POWER Button or stops showing up in MultiDownloader, The flash was successful.

12- Now you should be able to Hold download mode combo Power + Vol Down + Home and boot into DownloadMode

13- After which you can download your stock firmware from SamLoader / SamFW and follow various other guides online on how to flash your phone via ODIN Or heimdall

• Note : Since my S7 was bricked a couple times, on some occaisons i had to take the back cover off and physically disconnect the battery after flashing to reset the board. However holding Vol DOWN + Power for 15 seconds should trigger a force reboot