How can i install older firmware in mt7-tl10

the phone was soft-bricked (boot-looping in the huawei initial animation), when i failed to instal correctly the update from b326 to b511, the bootloader was locked and the phone wasn't rooted, but i managed to solve both things, then i tried to restore a twrp backup of b511, since that was the version i tried to update to in the begining, after the restore, it was stuck yet again in boot loop but this time it only shows the initial huawei picture, so my cuestion is if there is some way to reinstall an older firmware, say b326, because when i did a backup so i could use the folder to store the files for the b511, the containing carpet name included b326, or if someone has a twrp backup for b326 that could share, it would be really apreciated

cheers

p.d.: i don't know if i should use some sort of rollback or how to use it, so any guidance would be really helpful

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