Cannot Install Any New Updates On 7.2.9

[Andrius Kurtinaitis]

Hello,
after I upgraded to Nougat using the 7.2.9 build, now I cannot flash any new updates.
I tried to unlock the bootloader using the unlock tool. It succeeded, but on subsequent upgrade retries the phone reboots with the same old 7.2.9 version.
If I try the unlock tool again, it says it is not necessary to unlock (already unlocked?), but I still cannot upgrade.
The current version (7.2.9) heats horribly and depletes the batteries in half a day.
Any ideas what else can I do?

 

[shadowerwtas]

Are you trying to update through the Updater? Have you tried via straight via TWRP?

 

[Andrius Kurtinaitis]

Are you trying to update through the Updater? Have you tried via straight via TWRP?

1) yes
2) no
What's this twrp? Should I install it or it is already there? Flash it? What does it mean?

 

[Andrius Kurtinaitis]

Thanks all, I think I've found some answers at https://xiaomi.eu/community/threads/total-beginner-have-some-questions.39293/#post-360490