If your phone shows no sign of life (no red bar, no preloader), you need to force BROM mode.
If the error persists, try (Warning: This wipes your IMEI if you don't have a backup). Only do this if you have a full stock firmware backup. oppo a15 download not completed error fix oppo custom file
If your custom file came as payload.bin (Android OTA style), you cannot flash it directly. Use to extract the images ( boot.img , system.img , vbmeta.img ), then repackage them using MTK Customizer to create a valid scatter. If your phone shows no sign of life
A utility used to exploit the boot ROM vulnerability and bypass SLA/DAA authentication. If your custom file came as payload
Without this partition, the phone security handshake fails during boot. You can resolve this issue by flashing a dedicated back to the device partition. Why the Error Happens: The Anatomy of Error 0x992566