Cannot Update Redmi 3

[abdieldz]

I tried to install MIUI 7.10.26 but I always get the error unmount of /firmware failed and then Installing MIUI update, after that it just shows package_extract_file_took 00s and it gets stuck there. I rebooted and it stands on the MI logo.
I can flash the 7.10.12 MIUI and it installs well.
I also tried using this guide: https://xiaomi.eu/community/threads/solved-cant-reboot-to-recovery-from-os.41559/#post-387445

I'm using official TWRP 3.1.1-0

 

[MeiGuddet]

Seems your device is locked again. So re-unlock your bootloader with the Mi Unlock tool:
http://en.miui.com/unlock/download_en.html

 

[abdieldz]

When I had the MIUI 7.10.12 I flashed the emmc_appsboot file and it locked my bootloader so I unlocked it again then I tried to install the new release and the same happens TWRP says unmount of /firmware failed and doesn't finish the installation just gets stuck on package_extract_file_took 00s.

 

[Illumino]

When I had the MIUI 7.10.12 I flashed the emmc_appsboot file and it locked my bootloader so I unlocked it again then I tried to install the new release and the same happens TWRP says unmount of /firmware failed and doesn't finish the installation just gets stuck on package_extract_file_took 00s.

you have to unlock the BL officially via xiaomi.
xiaomi.eu doesnt support unofficaly unlocked devices.