Lenovo A820 Stock Firmware (Flash File) The Flash File will help you Upgrade, Downgrade, or re-install the Stock Firmware (OS) on your Mobile Device. In addition, the Flash File (ROM) also enables you to repair the Mobile device if facing any Software Issue, Bootloop Issue, IMEI Issue, or Dead Issue. File Name: Lenovo_A820_4.2.1_OTA.zip File Size: 340 MB How to Flash (install): Copy update.zip file to phone SD memory and flash it from Recovery Mode. (Mediafire)