Vivo X9S Plus PD1635 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: Vivo_X9S_Plus_PD1635_A_1.18.5_Update_OTA.zip File Size: 1.86 GB How to Flash (install): Copy the update.zip file to the phone SD and flash it through the stock recovery mode. Mirror 1 (Free)Mirror 2 (Paid)