[LG G8X ThinQ Questions & Answers] hey_sdk:
This is a Summary of how I managed to Brick my DualScreen case by Deleting the Firmware on the dual-screen chip. (and Possibly, How it can be fixed)

I was trying to make a Mod for the dual-screen case to be able to use it with other android or windows devices as a type-c display, Using a Type-C extension cable.
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I did a lot of googling and found THIS, apart from that I found nothing useful about the dual-screen case and how it works, so I had to do some digging of my own.I started by extracting all the APKs on my LG G8X that were related to the dual screen case And found an MCU (Microcontroller unit) named “STM32” mentioned inside the “dualscreenfirmware.apk” .dex file, After doing some googling I found that this type of MCU is used in chips like Arduino and other development chips.

Now I had some Basic idea of how the dual-screen case worked, after that, I had to figure out why the dual screen only works with the LG8X and not with the other devices,( yes of course it's because of the software inside the G8X), Again doing some googling brought me to this TEARDOWN video of the dual screen case, in the video I noticed that LG has used a lot of Magnets in the case. Now I did some experiments on my device and found THIS. LG uses these Magnets as the Trigger for the dual-screen case, When you insert the phone inside the dual-screen case the PHONE’s magnet sensor detects the case and activates the USB-C PD (Power Delivery) mode, and starts the Second display function. It also uses a specific type of type-C connection with VCONN, so it does not work when the phone is flipped.

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You can go to the Hidden menu on the LG G8X by typing this on the dialer app *#546368#*850# Here I found the Cover Display firmware update option and various other settings. The version of my Dual screen is PIC. There I found the Firmware file name ending with .dfu Again after doing some googling, I found that the STM32 MCU goes to DFU (Device Firmware Update) mode/protocol while updating or flashing the firmware.

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I was sure that I can now download and edit or make a firmware file of my own to use the Dual screen case on any device. So I Installed this APP (StmDfuUsb) on my G8X from the play store hoping that I will be able to download/extract the firmware file from the Case itself. I was yet to figure out how the Dual-screen goes to DFU mode for it to be detected on this App. After a lot of Googling and trying to figure it out for a while, I accidentally found it, I went to the Hidden menu and pressed the update cover display option, but this time a pop-up comes up saying open with this app(StmDfuUsb), so I click on it and voila, Now my dual-screen was in DFU mode and it was connected to the app,(as excited as I was) without thinking I tried to download the firmware file to the phone, but I ended up pressing the Erase Flash option instead, Bam... the dual screen went off right in front of me. (Not realizing what I just did) dual-screen was still connected in DFU mode (but stupid me) I removed my phone from the case and Re-Inserted it, but this time it only Connected to my phone as a USB, and changing the USB configuration did nothing but it reattached the USB connection. I went back to the hidden menu to put the dual screen back on DFU mode, and to update the firmware, It showed THIS ERROR, as the dual screen was not detected by the phone as a USB Device the phone was not able to get control of it, also the Buttons on the Case did not work,(At this point I realize that I F**dup) I Started downloading different Apps for USB and STM devices but found it all useless. Also, it does not get detected in windows pc as a USB connection, tried both on a USB A 3.0 port and Type- C port with a USB C extension cable.

After trying for a couple of days, I decided to take the device to the Service Center. I explained the problem to the LG technician “I accidentally deleted the firmware while working on an Arduino chip via OTG”, (of course I’m not gonna tell him that I was trying to modify it.) He tries to diagnose the issue and he told me that the problem was with the USB port on the case and it needs to be replaced, (He thought there was no firmware inside the Dual-scree case, I was Infuriated) After a few minutes of arguing with him, I told him to order the part, as he told me that they won't charge me anything if it didn't work even after the replacement ( the Type-C port was ₹1600 approx), and there, I return after two days to get the port replaced, and as expected the Dual-screen still in the same condition after USB port replacement (I told you so moment), So the technician now believes me and calls his senior management on phone, and now he does not understand the problem, he told me that they do not have the firmware seperately for the Dual-screen and they do not have the authority to access the firmware, they just replace parts, he said they can replace the PCB inside the dual-Screen, Now I know that will solve my problem as the new PCB will come with the Firmware built in, but it was not the solution I was looking for, I told the technician to place the order for the part (which costs around ₹1500), then I return home.

Now, I did not want to spend ₹1500 for a thing that can be fixed with the software. Thinking about this problem got me to blame LG for hiding the information and resources about the Dual screen, so I Emailed LG Service India Head and LG CEO office from the LG India website. Meanwhile, I also asked for High res pics of the PCB/Motherboard, from the same guy who did the TEARDOWN video and got it HERE. I also got the .DFU Firmware file from a guy with a Rooted G8X (The file is stored inside the phone under system files).

Now I know this problem can be fixed easily if LG reveals the information about the Dual screen and provides the Repair guide and relevant resources (Still Emailing them to escalate this Issue #RightToRepair). Also, I’m relying on the LG community and its developers that can help me get my dual screen working again. I have provided all the Information and resources that I think can solve this issue, if I’ve missed something please let me know.

My guess for possible solutions are-

An App can detect the USB device and put it in a different connection mode. (Possibly to DFU mode)

These Pins/contact points on the PCB can be used to put the device on bootloader/ DFU mode like on an Arduino chip. (I need to find the right jumper pins.)

Using the 3 Buttons on the case to put it in Bootloader/DFU mode. (I have tried a few combinations, but No luck)

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-SDK