I made this tutorial for those of you who commented that when re-flashing the redmi 6 cereus/redmi 6a cactus error (status sec img to large) or maybe something like this (status sec img type mismatch) you guys try to follow what I explained and here's the DA file for redmi 6 and redmi 6a
ATTENTION THIS: it is highly recommended, now flashtool without entering the authentication file again, without entering the download agent file again, to download the agent use the default version of flashtool v5.1952, but the condition is that you must use this version of flashtool ( v5.1952 ) already in the file complete mediatek
DA File Redmi 6a :
Mediatek Complete File: