The A Quantum is actually the A71 5G from South Korea Telecom but it contains an S2Q000 Quantum random number generator made by IDQuantique.

This is a systemless install which means you don’t bugger up the distribution. In a nutshell, Magisk patches boot.img and vmbeta.img which gives it a handy/dandy portal to rootworld.

• Download original firmware that matches the baseband version in the phone. e.g. from https://www.sammobile.com/firmwares/
• Download Heimdall: https://github.com/Benjamin-Dobell/Heimdall. The prebuilt packages didn’t work on my Mac (14.2.1 (23C71)) so I had to build it myself.
• Enable Developer mode on the device.
• Unlock bootloader.
• Install Magisk.
• Copy the AP firmware tarball to the phone. e.g.: adb push AP_A716SKSU6FWH2_QB69542795_REV00_user_low_ship_MULTI_CERT_meta_OS13.tar.md5 /sdcard/firmware.tar
• Run Magisk and click “Select and Patch a File”
• Select the firmware file you uploaded.
• Heimdall will patch the file and rename it to something like magisk_patched-27000_KHeEJ.tar
• Pull the patched file off the phone. adb pull /sdcard/magisk_patched-27000_KHeEJ.tar patched.tar
• Untar the file. tar xvf magisk_patched-27000_KHeEJ.tar patched.tar
• There will be a bunch of files. The ones I needed to flash were vbmeta.img and boot.img
• Find the parition names by running: heimdall print-pit --no-reboot They look like this:

— Entry #12 —
Binary Type: 0 (AP)
Device Type: 8 (Unknown)
Identifier: 7
Attributes: 5 (Read/Write)
Update Attributes: 1 (FOTA)
Partition Block Size/Offset: 14336
Partition Block Count: 10240
File Offset (Obsolete): 0
File Size (Obsolete): 0
Partition Name: BOOT
Flash Filename: boot.img
FOTA Filename:

Mine were BOOT and VBMETA.

• Flash them with heimdall: sudo heimdall flash --no-reboot --BOOT boot.img sudo heimdall flash --resume --VBMETA vbmeta.img
• When the phone reboots, you’ll need to wipe the filesystems.
• Once it comes back up, enable developer mode and install Magisk again.
• Magisk will perform the “final act” and the phone is rooted.