Here you can download Official SD Update Stock Firmware for the Micromax A84 Android device. The downloadable file High Compressed in an archive, You will get the Flash File after extraction. It contains Firmware and how-to Flash manual instructions.
[*] Chipset: Qualcomm MSM7627A.
[*] Driver: Qualcomm USB Driver.
[*] Firmware Type: Factory Update / OTA.
Firmware for Micromax A84
Build Number: MMX_A84_V07
Android Version: v2.3.6 (Gingerbread)
Download Size: 141 MB
[*] Backup: During the flashing process Firmware update will erase user data from the phone. So you need to backup for restoring those files on your device.