[Samsung Galaxy A70 Guides, News, & Discussion] fizzingbees:
For that follow MarvinMod guide on A70 > Los 17.1[unofficial] by grarak pg 16 forum

I am quoting his guide from there below.

Leave a thanks there

here is the proper way to install twrp ,los 17, gapps and magisk. ill provide links at end of post to make it easier. Many thanks to the dev [MENTION=4443334]Grarak[/MENTION]. Without his work, we would be without.. Note: you still can not backup\restore data but internal storage is decrypted. Also, Its the second formatting of data after setup that's getting decryption going *If you want faster access to enable wifi, pull your sim before this procedure. **You don't have to use wifi although I recommend it. You do need some kind of access to the internet. If you don't, knox will not let you flash and you could soft brick your device.

1. get the latest Android 9 Baseband/bootloader for your model using samfirm and flash using odin. setup device using wifi and enable dev options. make sure oem unlocking is on and grayed out saying the bootloader is already unlocked. shut down the device.

2. Hold both vol+ and vol- and plug into pc. hit vol+ on the next screen to enter download mode. flash twrp 3.3.1-6. when pass, hold vol- and power till device screen goes blank then immediately hold vol+ and vol- to boot back into download mode.

3. when your back in download mode, flash vbmeta. when pass, hold vol- and power till screen blank then immediately hold vol+ to boot to twrp.

4. click on settings and uncheck prompt to install twrp. go back. click on mount and make sure mount system partition read-only is unchecked

5. copy Los 17 20200213, open-gapps nano 20200127 (optional), and magisk 20.3 to external sd card.

6. Back in twrp, click wipe, advanced wipe and check ALL except micro sd card and usb otg. Slide right to confirm. DO NOT REBOOT. click back and click install.

7. click select storage and select micro sd card. click on los 17 then click add more zips. then click gapps nano (optional). swipe right to confirm.

8. once complete, go back and click wipe then click format data. type yes and enter. now reboot to system and wait.

9. setup wifi and skip the rest. enable dev options and select advanced restart. hold power and select restart then restart to recovery.

10. in twrp click wipe and format data, type yes and enter. then reboot back to recovery. internal storage should now be decrypted.

11. reboot to system and setup your device normaly. reboot back to recovery and flash magisk 20.3 and reboot to system. you should now have magisk in your app drawer, update it.

Links:

https://samfirmtool.com/

https://github.com/Grarak/android_device_samsung_a70q-twrp/releases/download/3.3.1-3/vbmeta.tar

https://github.com/Grarak/android_device_samsung_a70q-twrp/releases/download/3.3.1-6/recovery.zip

https://github.com/Grarak/android_d...213/lineage-17.1-20200213-UNOFFICIAL-a70q.zip

https://opengapps.org/

https://xdaforums.com/apps/magisk/official-magisk-v7-universal-systemless-t3473445

Ammeded guide by me

Google for gapp nano version. The open gaaps website offer different version

Unzip downloaded recovery zip to get recovery.img and repack it again with peazip windows program. Make sure to repack it as tar so the final file reads as recovery.tar. Also make sure this tar file doesn't contain anything besides recovery.img.

Flash both vbmeta and recovery.tar in AP slot of Odin v3.13.3. Uncheck reboot option in Odin