The device must be in EDL Mode (Qualcomm HS-USB QDLoader 9008). This is usually triggered by powering off the phone and holding Volume Up + Volume Down while connecting the USB cable.
, as they use different chipsets (Qualcomm vs. MediaTek) and will hard-brick the device. oppo a57 2016 firmware
For devices that won't start, you must use a PC-based flash tool. The device must be in EDL Mode (Qualcomm