I just bought this m35 on 6feb and it's facing drain problem so will it be fixed automatically or do i have to do anything although I've tried everything from background app to deep sleep and off wifi scanning

My m35 which I bought just a few days ago doesn't last long although it claims 6000mah battery it drain likes a river when I use it and doesn't give backup of even of 1 day even after doing all the things to save the battery please someone suggest me...