If your hardware buttons are not working or you are already connected to a PC for development work, you can use .
If your goal is to flash custom ROMs or root your OPPO A3s, your best bet is to use with the proper MSM Download Tool. Alternatively, explore unofficial methods that involve unlocking the bootloader via an authorized OPPO account (very rare and difficult). How to Open Fastboot Mode on OPPO A3s
The most common way to open Fastboot Mode on an Android phone is by pressing specific hardware buttons during boot. For the OPPO A3s, follow these steps: If your hardware buttons are not working or
A: Not officially. Some older software versions support it, but OPPO replaced it with EDL Mode on newer updates. The most common way to open Fastboot Mode
Always remember: tinkering with Fastboot or EDL can turn a functional phone into a brick. Proceed with caution, use reliable guides, and never flash files from untrusted sources. If your OPPO A3s is still under warranty, consider reaching out to an OPPO service center for advanced assistance.