Download the .img.xz file of your chosen ROM. Extract it to get a system.img file (usually 1.5GB - 2GB).
fastboot erase system fastboot erase userdata fastboot erase cache vivo y1s custom rom
Turn off the Vivo Y1s. Press Volume Down + Power until you see the Fastboot logo. Download the
Connect to PC. Open Command Prompt.
fastboot flash system system.img
Because the Y1s shipped with Android 10, it supports Treble. This means the device has a Vendor partition separate from the System partition. Consequently, you can flash GSIs (Generic System Images) . While there are few device-specific ROMs for the Y1s, the GSI community is vibrant. Prerequisites: What You Need Before Flashing Installing a custom ROM on a Vivo device is not as simple as on a Xiaomi or OnePlus. Vivo actively discourages bootloader unlocking. Proceed with extreme caution. Press Volume Down + Power until you see the Fastboot logo
The Vivo Y1s entered the market as a budget-friendly workhorse. Designed for basic tasks, it features a modest MediaTek Helio P35 chipset and 2GB of RAM. While Funtouch OS (Vivo’s proprietary skin) is stable for everyday use, it is often criticized for its heavy resource consumption, intrusive ads, and lack of timely updates. For power users and enthusiasts, this limitation is a call to action.