Oppo F1s Firmware !exclusive! Download - 7-1-2

The Oppo F1s originally ran Android 5.1 (Lollipop) and officially received an upgrade to Android 6.0 (Marshmallow) with ColorOS 3. OPPO India Community Update software – OPPO F1s - Android 5.1 Guide

Before attempting to flash a custom Android 7.1.2 firmware, ensure you have the following: Oppo F1s Firmware Download 7-1-2

The phone's bootloader must be unlocked to allow custom software. The Oppo F1s originally ran Android 5