Yes, but only under specific conditions.
Yes, flashing an via an SD card is a working method primarily used for updating software or fixing minor system issues like being stuck on the OPPO logo, provided you can still access Recovery Mode . Requirements Before Starting flash oppo a57 via sd card work
Since the phone is likely bricked, you cannot boot normally. You must use hardware keys. Yes, but only under specific conditions
: A formatted microSD card with enough space for the firmware file (usually 1.5GB to 3GB). Step-by-Step Flashing Guide 1. Prepare the Firmware You must use hardware keys
: Ensure your phone has at least 50% battery to prevent it from shutting down mid-process, which could permanently "brick" the device.
If you have a hardware failure (eMMC corrupt), no SD card flashing will work. Oppo service centers have proprietary tools to re-flash the bootloader for free (if in warranty) or for a small fee.