Originally Posted by doctor_whooves
Yes, I had to unbrick using msm. It worked. Was able to get phone rooted and stock recovery replaced with TWRP but it was a much bigger pain than I expected.
Glad you got it recovered.
There is an application called "Partitions Backup".
It allows you to back up all the phone partitions. The one you really want to backup from now on is the boot_a and boot_b.
Since you are rooted when you do an upgrade, grab the boot_a and boot_b before installing Magisk after the install.
This allows you to go back to stock. After you back them up, copy them to a computer.