Asus India — zenfone 3 max 5.5

Hi, i am very much unsatisfied with the asus zenfone 3 max that i bought. Because, first it was marshmallow and i was very happy that the phone has godd battery etc.. But after 4 days, nougat update came and i updated my phone to nougat.
But after this, the phone is draining battery, and very much heating.
So please provide a firmware to downgrade from nougat back to marshmallow. If you didnt do that in one week, then i will change my phone and will never try to buy asus again.
Please release the downgrading firmware within one week. Please.