I have a Teracube 2e (2020 SN), and it recently stopped booting. I can connect to it with SP Flash and download partitions, but fastboot doesn’t see it, and dmesg reports that the USB connection keeps closing itself after a few seconds. And, unfortunately, throughout all of this, the screen remains stubbornly blank, so I’m not even sure if I’m reaching any of the boot/recovery menus with various combinations of the power and volume buttons. Potentially, I’m facing a case of a/b booting, but with the display apparently non-responsive, it’s difficult to tell what’s going on (and without fastboot, I’m not sure that’s fixable anyway).
At this point, barring more clever troubleshooting ideas, I’d just like to copy off the data on the data partition and then send off the phone for repair/replacement. Unfortunately, while I can dump the user_data partition just fine, it’s encrypted. I have my PIN, of course, so then the question is how to find the encryption key, decrypt it with the PIN, and then use the decrypted key in turn to decrypt the dumped user_data.
Any suggestions (either about booting or decrypting) would be most appreciated.