Because VIVO S1 often defaults to a Factory Test Mode, you can sometimes find a Fastboot option within that menu.
Opening Fastboot Mode on the VIVO S1 is a straightforward process used for system recovery, firmware updates, or advanced troubleshooting. This mode allows you to interact directly with the device's bootloader before the main Android operating system loads. How to Open Fastboot Mode on VIVO S1
: Once the device is completely off, press and hold the Power button and the Volume Up button simultaneously. Because VIVO S1 often defaults to a Factory
If this option exists, your device will switch to the true Fastboot mode (usually a black screen with white text showing "Fastboot" at the top). If the option does not exist, your VIVO S1 does not have a user-accessible Fastboot mode. How to Open Fastboot Mode on VIVO S1