Ah indeed, that file does work. Thank you @Aje05
Filename also matches the build number of my phone if I go into ‘Settings’ → ‘About phone’ → ‘Build number’.
So yeah, downloaded, extracted ‘boot.img’, and followed the instructions at Installation | Magisk
Downloaded https://github.com/topjohnwu/Magisk/releases/download/v25.2/Magisk-v25.2.apk with my computer and pushed it onto the phone to ‘/sdcard/
’ using ‘adb
’. Also pushed the extracted ‘boot.img
’. After having the Magisk app patch ‘boot.img
’, adb-pulled the patched file back to the computer, now ‘magisk_patched-[random_strings].img
’, did ‘adb reboot fastboot
’, and then ‘fastboot flash boot magisk_patched-[random_strings].img
’ as in the instructions.
Rebooted back into system, did ‘adb shell
’ followed by ‘su
’ and can confirm that now have the root prompt ‘#
’.
Obviously prior to this had to unlock the bootloader as described at [ Advanced ] Unlock the Bootloader
The only thing I had a problem with is getting the bootloader locked again. Attempted to accomplish that by going back to fastboot and then doing ‘fastboot flashing lock
’. That command itself worked, but when I tried to boot back into the system it flashed an error regarding verification problems and went into a boot loop. So I got back into fastboot mode and issued command 'fastboot flashing unlock
'. That allowed me to get back into the system but of course the bootloader is still unlocked. Messing with the bootloader locking also did a factory reset; however, the phone is still rooted. I pushed ‘Magisk-v25.2.apk
’ back to ‘/sdcard/
’ and re-installed it, and it still detects itself on the boot partition and ‘adb shell
’ still allows ‘su
’. I attempted to disable the verification using the command ‘fastboot flash vbmeta --disable-verity --disable-verification vbmeta.img
’ as in the Magisk installation instructions but that kept failing with ‘FAILED (remote: 'No such file or directory')
’
So hope this is useful to whoever is also rooting their Teracube emerald. Much appreciation to @Aje05 for pointing out where the factory image is. Very glad to finally have found a phone that allows root access and user-replaceable parts.