Billow S51HD 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: Billow_S51HD_MT6582_03122015_4.4.2.zip File Size: 490 MB Flash Tool: SP Flash Tool for Windows | SP Flash Tool for Linux How-to Flash (install): Follow Tutorial Mirror 1 (Free)Mirror 2 (Paid)