I see you had the same version and configuration as me, how did you do the downgrade?
With TWRP or official flasher? Which recovery.img and B609 full rom did you use.
I tried to flash the official recovery back + the full B609 but the update always get stuck in "verifying update Package" for hours without moving... I feel that there is a problem with the recovery version.
try flashing ur current systems cust and recovery imgs then try downgrading to b609