[Samsung Galaxy A7 (2018) Guides, News, & Discussio] Wolve-San:
Hi everyone,

I had dozen of problems getting my SM-A750FN/DS with the newest Stock Rom to run any GSI Rom, until I tried something that did the trick. Since there are a couple people here, who can't get it running, too, I decided to write a little Guide. Do all things in the right order and it should work. Since I only have the SM-A750FN/DS, I can't promise, that it will work on other SM-A750X devices.

First of all: I am not responsible for anything you do to your device. This guide worked for me, it doesn't have to work for you.

Working so far:

- Calling

- WIFI

- Sensors (All)

Working partially:

- Cam

Doesn't work so far:

- Bluetooth

- Memory Card

- USB File Transfer

Before you start with anything, get this things on your SD-Card:

1. Quantum Stock 2.5 Latest Release (OneUI edition, not the GSI!)

2. LineageOS 17.1 Arm 64 BvS (Extract the XZ and copy the IMG to the SD)

EDIT: Updating to the newest GSI Rom works through TWRP! Just choose the newest LineageOS BvS, extract it and copy it on your device. Install the Image and choose ONLY System. After the reboot you will be up-to-date. Tested with LineageOS 17.1 15.06.2021 GSI Rom (AllArch).

Good, now we need to make sure, that you have the STOCK ROM running on your Phone. If not, download the newest Samsung Stock and flash it with ODIN 3.14.4.

1. Download ODIN 3.14.4

2. Start ODIN.

3. Click on AP and choose the Samsung Stock Image (DO NOT CLICK ANYTHING ELSE!)

4. Start on your phone the bootloader (normally it is VOLUME DOWN + POWER button, when you phone is off).

5. If that didn't start the bootloader, try VOLUME UP + POWER and choose Start Bootloader in the menu.

6. Connect your phone to your computer through a USB cable.

7. Click Start in Odin (on your computer).

8. Wait for the phone to start into Android.

9. Close ODIN

10. Connect your phone to the internet and put a SIM inside (without this your OEM Unlocking option won't appear)

11. Enable Developer options in settings. Normally found after click about 10 times on Build in Settings ---> About Phone. (Here you can also see, that your phone uses OneUI 2.0.)

12. In the developer options you enable OEM Unlocking (this will delete everything on your phone - like a factory wipe).

13. Restart your phone and check if OEM Unlocking is enabled. If it doesn't appear, you are not connected to the internet and your sim card is not unlocked.

Now you are ready to start the flashing of the new ROM.

1. Download TWRP by ashyx.

2. Power Off your phone and load it into bootloader/download mode.

3. Start ODIN, click on AP, choose the ZIP file containing TWRP, click on Options and DISABLE Auto-Reboot (VERY IMPORTANT!).

4. Click on Start in ODIN and wait until it shows PASS.

5. On your phone hold VOLUME DOWN + POWER, until the phone shuts off, IMMEDIATELY hold VOLUME UP + POWER, so the phone can start TWRP.

6. In TWRP go on WIPE, FORMAT DATA and type yes.

7. When it is done, go on the Menu button (arrow showing up), go on Reboot and on Recovery. DO NOT POWER OFF THE PHONE OR RESTART IT TO SYSTEM!!!

8. After the phone rebooted into TWRP go on Install.

9. Click on INSTALL IMAGE.

10. Choose lineage-17.1-20201114-UNOFFICIAL-treble_arm64_bvS.img.

11. Flash it.

12. After flashing is done, go back to menu (DO NOT RESTART THE PHONE YET!)

13. Go on Install and choose Quantum-Quack-A750F-V2.5-ONEUI.zip and flash it.

14. Wipe Dalvik Cache and restart the phone to system.

15. The phone will restart twice, on the second restart LineageOS will start.

You don't need magisk, since the Quantum Kernel is prerooted. If you wish to, try to install Magisk. DO NOT WIPE THE STOCK ROM!

For anyone ending up with problems:

ERROR: Download Mode shows "Only original firmware..."

Solution: You didn't check, if OEM Unlocking is enabled. IT IS NECESSARY TO CONNECT THE INTERNET AND SIM CONNECTION!

ERROR: Bootloop

Solution: Reflash the stock rom from Samsung and try the tutorial again. This time read more careful and don't miss anything. It is important, that your ABOUT PHONE says, that you have ONEUI.

ERROR: LineAgeOS doesn't boot.

Solution: Be sure, that it says BvS in the filename. AvS doesn't work, since Samsung changed the phone from a-only to A/B. Be sure to check if it is ARM64!

Special Thanks to:

@prashantp01 for the great Quantum Kernel 2.5!

@ashyx great working TWRP build!

@AndyYan for the unofficial ALLARCH LineAgeOS GSI. Works great so far.