I'm currently on Android 5.* and I wanted to upgrade it to 6.0 - I downloaded official firmware and the tutorial gave me 2 ways of installing it. One way is through system (Settings -> Updates -> ... -> Local Update) and the other way is by holding appropiate buttons while booting. I HAVE copied update.app to external SD into 'dload' directory! The problem is, that my device has TWRP installed and whenever I want to upgrade firmware, it sends me to TWRP instead of sending me to upgrade recovery section.
In fact, I can get to EMUI upgrade recovery mode, but when I do, it just 'checks' the update file and second after starting to install it, it says, that install has failed. I'm 100% sure firmware is correct and I'm doing everything as I should.
The question is: Is there any other way of installing Android 6.0 on my device? It is rooted and bootloader is unlocked. Maybe I can do it somehow through bootloader?